'87 Pathfinder-Rear wiper won't turn off

[Fbanks]

Hi everyone,

I have a 1987 Pathfinder (SE) and the rear wiper will not shut off unless I remove the fuse. I had assumed perhaps the switch on the dash was bad, as the wiper goes the same speed whether it's in the intermittent, off, or on position. It will actually release wiper fluid if I push it all the way to the right, but other than that, the wiper does not react to the switch position. I did access the rear wiper switch on the dash, and pulled it out. Wiper does not activate with switch removed. I took the switch apart and looked it over, and it looks pretty simple. Springs for the contacts looked good, and the contacts on both the slider and the plug end looked clean, so no obvious issues. I don't have the pinout to test this, so if anybody has that, and/or the pinout on the rear wiper motor side, that would be awesome. 

 

My guess now is something to do with the wiper motor. I'll plan on taking the back hatch cover off to take a look. If anyone can direct me to a pinout for the connector there, I'll check out the different switch positions to make sure all looks good on that side. Then if that checks out, I guess it's down to the motor itself. I understand there is a contact in the wiper motor that tells it when it reaches the stop/rest position. Perhaps something is wrong there. I do notice that my wiper never goes all the way down to the rest bar, but I was thinking this was normal during operation, since the wiper blade is beyond the window pane when it rests on the rest bar. I guess the way it's supposed to work is that once the switch goes to the off position, then the contact should send it farther down past the window to the rest position, once it's triggered (and the switch is in the off position). Perhaps the contact is bad? If anyone can confirm whether the wiper should go fully to the rest bar even during operation, or only once the switch is in the off position, that would help. And if there's a procedure to adjust the wiper arm or motor contact, that would be very much appreciated! 

 

I should mention that this problem seems to have occurred at the same time that I had a fusible link burn up. The truck was operating fine (according to my brother who was using it), when power to the instrument cluster was lost. The truck continued to run fine, and he continued home with the truck, and let me know what had happened. I turned the ignition on to verify, and the rear wiper immediately came on, and I smelled a burning smell. My brother said the rear wiper was not running for him, though it's possible he just never noticed. I pulled the fuse to the rear wiper, but continued to smell the burning smell. When I looked under the hood, I could see a fusible link that had pretty much burned through. I've since replaced that, and the instrument cluster seems to be operating fine. I no longer smell the burning, and the fusible link does not seem to be getting hot, although I"ve not operated the truck for very long since. The rear wiper continues to run continuously, unless I pull the fuse. 

 

I cannot be sure that the fusible link issue is related, but it seems coincidental, so I wanted to put that information out there. Thanks for any and all help!

 

Edited May 17 by Fbanks
correction

[Fbanks]

I removed the rear panel, and was going to upload a video (17 seconds) of the rear wiper at work, showing the motor, switch, and mechanics at work. However, it would not let me upload a video, so I'll try to describe it. I did see a single mechanical switch that appears it should be pushed in when the wiper arm returns toward the rest position. However, the mechanical arm that rotates around never actually touches the switch. I thought for sure this was the problem, but even if I manually push the button on the switch and hold it in for a couple of revolutions, the wiper never stops. I did try it in all positions of the rear wiper dash switch, just to be safe. I'm not sure why whis would be, unless I'm unlucky enough to also have the dash switch never actually telling the motor to shut off, or if there's a short/open somewhere. In any event, it seems I have a problem with the switch by the motor not being activated. Does anyone know how to adjust the mechanical arm so that it would activate that switch? If you could see the video, you would see that the wiper arm doesn't actually go all the way down to the rest on the returns. That might relate to why the switch is not being pushed in. 

 

Actually, as I'm looking at the video closely, I can see there is some adjustment possible for the switch itself. I'm not sure there's enough play in the mounting to allow the switch to be activated, but I'll check that out more closely tomorrow. I'm also not sure why the switch would have moved/need adjusting? Is there also an adjustment that can be made on the rotating arm? That seems more likely in need of adjustment, since it's in constant motion when the wiper is on. Assuming I can get this sorted out, then it still seems I have a problem, since the wiper doesn't cut off when I manually depress the switch by the motor. If I had a pinout of the connector that plugs into the motor, and an explanation of how it works, I could at least eliminate any issues upstream of the rear wiper and motor. A pinout of the switch itself would also be nice. 

Edited May 18 by Fbanks

[Slartibartfast]

I've got an '89 service manual on Dropbox. EL-70. Hatch guts should be the same AFAIK. If it doesn't match up, let me know and I'll check my paper copy of the '87.

 

I screwed around with the linkage in my rear hatch once, maybe ten years ago. It wasn't acting up, I was just curious and in the neighborhood anyway (messing with the switch for the rear dome light IIRC). I remember the mechanism being a little more complicated than I had expected. IIRC the wiper has two resting positions, and only one of them hits the switch that allows the electric rear hatch popper to work. If the manual doesn't get you there, let me know and I'll open mine up and remind myself of how it's supposed to move.

 

Do not adjust anything until you know how it all works. The switch did not likely adjust itself between when it worked and when it didn't, so messing with it will probably just make more work for yourself once you find what's really wrong.

 

This sounds like a wiring fault to me. I would check the wiring between the hatch and the body for broken wires and cracked insulation. Could explain the burned fuse link and the motor getting power when it's not supposed to. Failing that, I would check the wipers in the motor that keep it going back to its home position, but it sounds like you did that already, and I would not have expected those to take out a fuse link. And, yeah, wouldn't hurt to check the switch as well, though again I don't think that would've killed a fuse link.

[Fbanks]

8 hours ago, Slartibartfast said:

I've got an '89 service manual on Dropbox. EL-70. Hatch guts should be the same AFAIK. If it doesn't match up, let me know and I'll check my paper copy of the '87.

 

I screwed around with the linkage in my rear hatch once, maybe ten years ago. It wasn't acting up, I was just curious and in the neighborhood anyway (messing with the switch for the rear dome light IIRC). I remember the mechanism being a little more complicated than I had expected. IIRC the wiper has two resting positions, and only one of them hits the switch that allows the electric rear hatch popper to work. If the manual doesn't get you there, let me know and I'll open mine up and remind myself of how it's supposed to move.

 

Do not adjust anything until you know how it all works. The switch did not likely adjust itself between when it worked and when it didn't, so messing with it will probably just make more work for yourself once you find what's really wrong.

 

This sounds like a wiring fault to me. I would check the wiring between the hatch and the body for broken wires and cracked insulation. Could explain the burned fuse link and the motor getting power when it's not supposed to. Failing that, I would check the wipers in the motor that keep it going back to its home position, but it sounds like you did that already, and I would not have expected those to take out a fuse link. And, yeah, wouldn't hurt to check the switch as well, though again I don't think that would've killed a fuse link.

 

Thank you for your help! I've printed out the relevant pages, and will take a look at the signals coming to the motor. So the switch I saw was likely then the hatch switch that you're mentioning. I'll try to remember to verify that. If that's the case, then I expect it only gets activated when the wiper fully goes to the rest position (resting on the rest bar), which only happens (or should) when it is shut off. Then there must be another switch/contact somewhere then that notifies the motor when the wiper gets to the stop/return position (close to the edge of the window, as opposed to the rest bar). 

 

You mentioned the "wipers in the motor that keep it going back to its home position". I'm not sure exactly what you're referring to there, so I'm not sure I did check that out.

 

I'll do some more investigations and report back what I find. Thx again!

[Fbanks]

Update- using the wiring diagram you gave me, I checked the switch, and it operates as it should with the switch in all the various positions. So I'm confident the issue is not in the switch.

 

While I had the switch out, I went ahead and checked some voltages on the connector coming into the switch (conn. # 211). From the diagram, i could see pin 8 (black wire)= ground, so I used that for my ground (please tell me if I'm mistaken here). Pin 9 (blue/black wire) read 12V, and the rest were all close to 0, except pin 1 (white/blue wire), which read 9.1V. Something seemed obviously not right there, unless that line just floats when not connected. Following the diagram back, I see the white/blue goes through a few connectors, but eventually comes from the rear wiper amplifier at connector #48. I was unable to locate this amplifier, so I can't check the output there, but my guess at this point is that this amplifier may be the problem, since the white/blue wire seems to originate from there.  If you can tell me where this is physically located, I can try to verify further.

 

I did find the rear wiper relay, and checked voltages there. Using the black wire on connector #118 as ground, all voltages read 0 except the 2 green/red wires, which both read 12v. If I disconnected the relay and read the voltages again at the dash switch connector #211, then I got 0V everywhere (except pin 6, if I recall correctly, which gave some small voltage reading of 0.1-0.2V).

 

I did confirm the mechanical switch I was looking at before was the back hatch disable switch, that apparently only gets pushed in when the wiper arm goes all the way down to the rest bar. 

 

Am I on the right track here, or do you have some better suggestions for me to try?

Edited May 18 by Fbanks

[Fbanks]

I'm looking at the diagram a little more, and what I wrote above, and something else is bothering me as well. I read 12V on pin 9 (black/blue wire) of connector #211, but I note that the switch will short pin 8 (ground) to pin 9 in the on/interval positions. This seems like it would be problematic too. The black/blue wire also originates from the rear wiper amplifier, if I'm not mistaken. I'm going to check the documentation you gave me to see if it gives some explanation of the pinout, and what exactly each of the wires control (inputs vs outputs, function, etc.)

[Fbanks]

I did another check at the motor itself- with the wiper running, I checked the voltage from ground (black wire) to the blue/black wire- this read a pretty constant ~11.9v, and did not seem to fluctuate with the arm position. I also read the voltage on the solid blue wire at the motor, and this voltage definitely fluctuated, mostly being at 0, but spiking each time the wiper arm went toward the stop/return position. I only have a multimeter and no o-scope, so I can't tell exactly how high the voltage spike was, but it looked to be north of 10v, so I would say it probably reached ~12v and my meter just wasn't able to capture it. 

 

I checked this same voltage on the blue/black wire at the relay, and it also read a pretty constant ~12v. While I was at the relay, I also checked all the pins coming in to make sure there were no shorts to ground at the relay, and I found none (except ground itself, of course). 

 

I'm thinking this means my motor is good, but please correct me if I'm wrong. The problem seems to point to either the amplifier, or potentially a wiring fault somewhere. I suppose it's possible the same fault that caused my fusible link to burn could also have damaged the amplifier at the same time. 

 

I'm guessing that amplifier is in the side panel on the driver's side. Do those plastic panels just pop out, or is there some trick to it?

 

P.S.- I'm not sure my Pathfinder matches exactly your diagram, as except for the one unused pin it shows on the motor connector, I have wires connected to all pins on the connector, while the diagram from your manual seems to show 2 unused pins on the left side of the connector in the diagram. i'm not sure that's important, or if those wires are really used, or just extra unused wires. 

Edited May 18 by Fbanks

[Slartibartfast]

Black at 211 is indeed ground. Blue/black should have 12v when the key is on and the wiper relay is not energized, so that sounds right. White/blue should have 12v power with the key on and the hatch glass closed, so, yeah, 9.1v says you have some investigating to do there. It gets power from the same place blue/black does (green/red), so you know the wire coming back from the dash is OK. I would check the glass hatch switch (in the latch). If it's closed, but you're only getting 9.1v after it, yeah, something ain't right. Test for the missing voltage across the switch.

 

If the switch is open, and you're seeing 9.1v after it, it could be backfeeding power from elsewhere in the circuit. I don't know that it should be doing this, but I also don't know that it shouldn't. If white/blue gets 12v when the hatch is shut, I would note the weird voltage but not chase it unless I run out of ideas or something else makes it make sense. If it's 9.1v regardless, that's a problem.

 

I would expect this problem would stop the wiper, not make it run constantly, but I don't know how the amp works.

 

I guess in this context "wipers" is vague as hell, sorry about that. I meant the contacts in the motor that keep it powered until it reaches its home position. There's a little metal finger that spins with the wiper crank, and a C-shaped track that it runs on, with the gap at the home position. So if you turn the wiper off when it's not in its home position, this setup is what keeps it powered until the wiper is home (and the finger finds the gap, breaking the circuit). Looks like this switch hooks to black (ground), blue, and blue/black. It's the pac-man looking thing under the motor symbol in the diagram on EL-70. The pulsed power you're seeing on blue makes me think this is probably OK.

 

EL-91 shows where the amp and relay are located.

 

My money's still on a wiring fault, but, yeah, I wouldn't be shocked if it took out the amp, too. The thing that's confusing me is how it took out a fuse link but left its own 10A fuse intact. That makes me think another circuit may be involved--and, yeah, depending on what shorted to what, that might've screwed up the amp. Or maybe the fuse link was just old and corroded and failed under normal load, though I'd be surprised if under-voltage took out the amp.

 

I would be tempted to give the wiper amp a good thwack with a screwdriver, on the off chance that frees up a stuck relay contact and brings it around--but I would be surprised if this fixed it.

[Fbanks]

Thanks a lot for the suggestions, I'll try to do a little more tomorrow when the weather is cooperating better. You mentioned a fuse blowing and another circuit, and it made me think of something else that I should have mentioned. I remember after replacing the fusible link, turning the ignition on to test things. Everything seemed normal, but I noticed that my power locks were not working. I pulled the fuse (10a, as I recall), and it was burned. I replaced that fuse, and the locks returned to operating normally. I didn't think about it again until your mention above of a blown fuse and another circuit, and it rung a bell. 

 

For sure, the fusible link did look quite old and there was noticeable corrosion around the terminals. From the looks of it, I do believe this had been replaced one time before, as it was clearly not the stock connectorized fusible link that is shown by Nissan (Nissan part #24021-V5112). Maybe the replacement fusible link was undersized? I'm not sure what gauge that fusible link should be,  but I think I read somewhere it was 16 gauge, but I wasn't sure this was right. I used 14 gauge based on the size of the terminals/spade connectors, but that was just a guess. I actually would have guessed 12 gauge, but I was afraid to go with too large of a fusible link and defeat the purpose. This is the fusible link that powers the instrument panel (i know just because nothing on the instrument panel was working), and based on the blown fuse, I guess the power locks as well. I don't know if this same fusible link ties into the rear wipers, but I guess that might make sense with the switch being on the dash. 

 

It looks like there's a connector right there by the switch for the glass hatch, so I should be able to disconnect the switch easily enough, and open or short the connector and check the voltage on the white/blue wire (pin 1 of connector 211) easily enough. If that solves the problem, then I'll know it's the switch. I'll let you know what I find.

 

Many thanks again for all your help! I'd be like a blind squirrel here without your advice. 

Edited May 19 by Fbanks
corrected pin 9 of connector to 211 to pin 1

[Fbanks]

Well, I thought I had confirmed the rear glass switch was the problem. First, I disconnected the connector to the switch, and monitored pin 1 of connector #211. Before this was ~9v with the rear glass closed. When I disconnected the switch, I also got 9v, so I guess an open on the switch corresponds to hatch closed. Next, I shorted the connector going to the rear glass switch, and the voltage on pin 1 of #211 dropped to 0v. 

 

Next I decided to ohm the switch itself. On the connector coming from the switch, I read an open with the rear glass open. With the rear glass closed, I noticed the ohmage fluctuating, though it did eventually settle down to around ~2-3 ohms. I jiggled the connector a little, and noticed large fluctuations. I thought the wiring was probably bad, but luckily I have some long springy leads where I was able to reach directly on the contacts of the switch. I noticed these same fluctuations when I manually depressed the switch button, so I thought for sure the switch was my problem. I sprayed some electronic cleaner on the switch and got it to where it was reading 0.8 ohms with the button out, and an open when the button was depressed. I felt sure this would solve my problem. 

 

I decided to test with the rear glass switch disconnected. I started with the connector going to the switch shorted, to emulate the rear glass open. Sure enough, when I did this, the rear wiper would not operate, regardless of the dash switch position. Next, I disconnected the  jumper on the rear glass switch connector, thinking I should have normal wiper operation. Unfortunately, the rear wiper would not shut off, as before. I was puzzled, so I went back to the rear glass switch leads. I noticed that with the rear glass closed, I was not seeing a full open on the switch any longer, but instead something like 265 ohms. I thought maybe the switch was bad, but when I disconnected the switch from the wiring harness, I noticed it now showed a solid open again. I then ohmed the other side of connector #160 (coming from the wiring harness) and I also read ~265 ohms between the wires going to the switch. 

 

From this, it appears that there is some issue between the blue/white wire and green/red wire going to the switch. I disconnected the dash switch just to see if that made any difference, and it did not. I then disconnected the rear wiper relay at connector #118, and I then measured an open on the rear glass switch with the glass closed. Could the rear wiper relay be bad, and this causing the issue? I was hoping I might have another elsewhere in the truck I could swap it out with to test, but I did not see one at a glance. I'll try to see if the manual shows a test procedure for this relay. 

 

 

[Fbanks]

I just thought of another quick test I could do. Since I noticed the issue only with the relay in place, I decided to unplug the relay, and check the ohmage between the blue/white and red/green wires on connector #118 coming into the relay. This showed an open. Since on the rear glass switch end, it also showed an open between these wires without the relay, I figured the issue must be the relay itself. When I ohmed the pins on the relay corresponding to those wires, I also saw an open, which surprised me since I was expecting to see the 265 ohms. Next, I got on the back of connector #118 with some paper clips, and read the ohmage between the blue/white and red/green wires. With the relay in place, I read the 265 ohms. When I unplugged the relay, I read an open. I'm not sure if this means my relay is bad (that would be my guess), or if somehow the relay is working properly but enabling some other path through which I'm reading the 265 ohms.

 

Assuming it is the relay, any ideas on best place to get this?

Edited May 19 by Fbanks

[Fbanks]

I noticed that there were 2 Green/Red wires going to the relay, and I only checked the relay contact of one in my test above, so I took some more resistance readings on the relay itself with no power applied. I'm not sure what to expect or if this is really useful. But I noted the following:

 

resistance across contacts 1-2 (as labeled on the relay)=75 ohms (contact 1 should be GND, while 2= blue/white wire)

resistance across contacts 3-4= 0 ohms (contact 3 should be Blue/Black wire, while 4= Green/Red wire). Contact 4= top contact on the relay as shown in the manual

All the other pairs showed an open circuit

 

From the diagram in the manual, it looks like the readings on 3-4 could be normal, depending on voltage applied to the other contacts. Contacts 1-2 go across the windings of the relay. I'm not sure what that reading there should be, but I do note that the blue/white wire is involved here.

[Slartibartfast]

 

Hopefully the corrosion was what killed the link. Gotta wonder what popped the locks fuse. There is a power lock in the tailgate, so, yeah, could be something going on between the two. Again, I would check the wiring between the roof and the hatch.

 

Relay sounds OK. Should be some resistance across the coil, continuity across the normally closed contacts, open across the other two. If you apply 12v to the coil, the normally closed contacts should be open, and you should have continuity across the other two.

 

Are you testing the switch while it's plugged in? Testing components while they're hooked up is a great way to confuse the hell out of yourself. If it tests good when it's unplugged, the switch is OK. The only tests I'd do with the switch plugged in is check for power across it (assuming you can get to it without putting your fingers in the way of the linkage). If the switch is closed, and you've got significant power across it (I would expect millivolts, but not many of them), something ain't right. If in doubt, temporarily bypass the switch (jumper leads work great for this) and see if that clears up the issue.

 

Is red/green getting 12v?

[Fbanks]

15 minutes ago, Slartibartfast said:

Are you testing the switch while it's plugged in? Testing components while they're hooked up is a great way to confuse the hell out of yourself. If it tests good when it's unplugged, the switch is OK. The only tests I'd do with the switch plugged in is check for power across it (assuming you can get to it without putting your fingers in the way of the linkage). If the switch is closed, and you've got significant power across it (I would expect millivolts, but not many of them), something ain't right. If in doubt, temporarily bypass the switch (jumper leads work great for this) and see if that clears up the issue.

 

 

See my post 3 posts above your last one. Initially, I tested the switch with the switch disconnected. That's when I observed the initial fluctuations on the switch with the hatch open (switch closed). I cleaned the switch up the best I could, and then got stable readings (~0.8 ohms with switch closed, and OC with switch open). With the switch disconnected, I decided to test the wipers with a jumper in place of the switch, as you suggested here. That did not resolve the issue, and rear wiper still would not shut off. I also note here that with the switch disconnected (this should correspond to glass hatch shut), the white/blue wire on connector #211 still read 9.1v. When I jumpered the switch connector (hatch open), this voltage dropped to 0v (and inhibited rear wiper operation, as it should). 

 

The 265 ohms I read across the switch was after my jumper test failed, and yes, this was with the switch connected (and relay connected). I will check the voltage across the switch as you suggest later tonight, hopefully. I'll also check red/green at the switch. Reading back, I just noticed that I did check the red/green lines at the relay, and they did read 12v, so I expect it should be fine at the switch as well. 

 

I guess one thing I keep wondering is why the 9.1v on the white/blue wire at connector #211? While I don't know exactly how that amplifier works, I note that the white/blue wire goes between the dash switch and the amplifier, and does not appear to go anywhere else. So my question is then whether the white/blue wire is an input or an output of the amplifier? If it's an output from the amplifier, wouldn't that mean a problem with the amp? Or perhaps that output is dependent on the inputs to the amp?

 

I was hoping to avoid it, but it seems like I'm going to have to take off those side panels to get to that amp and take some readings there. I can also ohm out the white/blue wire with the dash switch & amp disconnected, to verify whether any wiring issue there, as well as all the other wiring. Then, if all the voltages at the amp seem normal and I don't see that ~9.1v somewhere, then it seems like it would have to be an amp issue. I'll double check again, but as I recall all the voltages at the relay seemed normal. 

 

For the wiring between the roof/hatch, there looks to be a rubberized conduit through which the wires pass. It doesn't look damaged in any way, but that doesn't mean the wiring inside might not be. I think getting access to the amplifier and connections there may be necessary at this point. 

 

 

 

 

[Slartibartfast]

Sorry I missed that. This kind of thing is a pain to diagnose over the internet via text, especially given how unexpectedly complicated this wiper circuit is.

 

Blue/white doesn't go to the amp at all. Green/red carries fused + to the glass hatch switch. When the hatch is shut, blue/white carries power from the switch to the relay coil (you should be able to make the relay click on and off by playing with that switch) and to the switch on the dash. If the switch is set to on or intermittent, it connects blue/white to red/blue, which goes back to the relay, through the normally open contacts (closed now that the relay is active), to green/red, the fused + feed again. All I can figure is that this is latching the relay--so if the relay is engaged (ignition on/hatch closed), and the rear wiper is on or intermittent, opening the hatch switch won't disengage the relay, because it's passing power to its own coil, effectively bypassing the glass hatch switch. This would make the wiper keep going if you opened the hatch with the key, which seems like it would be a bad thing--though I guess you can't open the hatch with the key when the key is in the ignition. There must be some reason it's set up like this--but I don't think that rabbit hole has the answer to this problem at the end of it. (Assuming I'm following the lines on the diagram correctly.)

 

The takeaway I'm going with is that power on blue/white should make the relay click.

 

If the relay isn't working, and it's leaving the normally open contacts closed when the coil is powered, it would be applying fused + to blue/black. I have no idea what effect this would have. Might be confusing the amp? Pull that trim panel, test the relay. Make sure it's good, and make sure it clicks when you turn the key on with the glass closed. If the relay is OK, but it isn't getting enough power from blue/white to click, chase that low voltage. If it's working how it should, I would rule it out for now.

 

It looks like I was wrong about the contacts on the motor powering it directly. Blue from the contacts goes to the amp. So the contacts don't run the motor directly--they tell the amp to do it. I'm also seeing a the blue/black wire, running to the "wash" position on the switch, which I assume grounds out that same blue wire when the washer pump is running. If blue or blue/black is grounded out, this would cause the amp to run the wiper motor whenever the ignition is on. Sounds like your testing has ruled this one out, though.

 

The amp has pretty much full control of the motor. Blue/yellow goes straight from the motor to the amp. Blue/red goes to the switch, which grounds it (along with the white/blue wire to the amp) in the "on" position, or connects it to the amp via the black/blue wire in any other position. If the dash switch is good, and neither of the blue/black wires (there are two black/blue wires in the same plug) are grounded (telling the amp to run the motor), then, yeah, that points to the amp.

 

The trim panel should come out without too much fuss. If it's like its counterpart in the four-door, it's just a grab-and-pull job, apart from the very back lower bit that's hooked under the plastic trim at the back of the cargo floor. If that trim has the same stupid plastic screws that mine does, I recommend a flat-blade screwdriver, with as little downward force as possible, until you can hook a fingernail under them. They push in, which makes them impossible to unscrew with a Phillips driver. It is possible to get the side panel out around the floor trim, but in my experience it's more difficult that doing it right.

[Fbanks]

2 hours ago, Slartibartfast said:

Sorry I missed that. This kind of thing is a pain to diagnose over the internet via text, especially given how unexpectedly complicated this wiper circuit is.

 

Blue/white doesn't go to the amp at all.

 

Hi, I haven't finished reading the rest of your post yet, but I wanted to be sure we're on the same page first by clarifying something. The wire on dash switch  (connector #211) where I'm reading the 9.1 volts is the white/blue wire (pin 1), not the blue/white wire (pin 2, I believe). Hopefully I didn't screw that up somewhere in my postings. According to the diagram you provided on EL-70, this goes to the amplifier. I don't see where it goes anywhere else. Since everything else on connector #211 showed either 0 or 12v, then I'm assuming that 9.1v is an output coming from the amplifier (the switch itself tested good, per my earlier post). Am I missing something here? 

Edited May 21 by Fbanks

[Fbanks]

1 hour ago, Slartibartfast said:

Pull that trim panel, test the relay. Make sure it's good, and make sure it clicks when you turn the key on with the glass closed.

I do have easy access to the relay through the little removable door just in front of the turn signal. I have had that relay exposed during my testing. I don't recall ever hearing it click, but I can't say for sure that I've actually been back there during the right conditions. It's easy enough to replicate, so I'll do that first chance I get. While I'm at it, I'll also check all the voltages at the relay to make sure I don't see anything abnormal there. I don't see a switch for the rear tailgate itself, so I'm assuming it being open shouldn't impact anything. 

 

Based on my earlier tests, I can say for sure that when the hatch was open, the wiper shut off, and would not operate in any position of the switch. This also dropped the voltage on the white/blue wire at connector #211 to 0V from the 9.1v. 

 

 

[Slartibartfast]

Yep, I got those crossed up in my mind. Good catch. Looks like the dash switch grounds that wire, so I'm guessing there's some transistorized something or another in the amp (not just relay logic) that's applying a little voltage to that line so it can tell when it's grounded by the switch. I would assume that's normal.

 

There is a switch for the tailgate (built into the latch), but it's not part of this circuit.

 

Sounds like the switch for the hatch glass is doing what it's supposed to do. Hopefully the relay gives you a smoking gun.

[Fbanks]

I had a little time before it got dark, and so checked out the relay/hatch switch. When I toggled the switch, I did not hear the relay clicking, and the wiper also did not stop. I was puzzled, because I was sure I had tested this before and the wiper would not operate with the switch in closed position. Looking back at my post, I'm not sure I ever actually tested this with the switch in place, but I instead had tested with a jumper in place of the switch. In any event, it looks like the switch is definitely bad, as when I checked across the terminals I got 12V even when toggling the switch, regardless of position. I disconnected the switch and ohmed it out, and sure enough it was now a solid open, regardless of the switch button being in or out. So it looks like I have a bad switch now that I should replace. It looks like I have to take the latch off (4 screws?) to access the switch. Anything I need to be aware of before taking that off, or is it just bolt on/off?

 

Regardless of the switch problem, I don't think that explains the root of the wiper never turning off. The switch should be an open when the hatch is closed, allowing the wiper to operate. The switch would never be closed so long as the hatch is closed, so effectively, the wiper should think the hatch is always closed with the switch being in the stuck open position. This should not prevent the rear wiper from turning off. 

 

While I had the switch disconnected, I went ahead and tested the relay by shorting the switch connector with a jumper. I could definitely hear the relay toggling, and the wiper would not operate regardless of the dash switch position with the jumper in place. It got dark before I could take any more voltage readings.

[Slartibartfast]

Interesting. Agreed that it shouldn't be the problem, but odd that it's out at the same time. I guess it could've been out for quite a while without being noticed. I've had the latch off of mine a couple of times (I added a second switch to it so it turns on the cargo light when it's unlatched), and I don't remember it giving me too much trouble going back together. The four bolts on the plate shouldn't give you a problem. The two holding the latch to the plate have slotted holes for adjustment, so draw around the latch (or the bolt heads) with a marker before taking those out so you can put it back where it was.

 

I had a look at mine to refresh my memory on how the wiper's supposed to work. With the switch set to intermittent, the motor turns counterclockwise (from my viewpoint under the hatch), and the linkage stops just short of the lockout switch for the hatch popper. When I turn the switch off, the motor turns clockwise, parks the wiper, and depresses the switch. This confirms that the gap to your hatch popper lockout switch is normal, for whatever that's worth.

[Fbanks]

Thanks for checking that out- yes, it is helpful. I can do without the hatch switch for now (easy enough for me to just remember not to pop the hatch with the wiper running), but if you know of a good source for that, I'd appreciate it. I have a hard time finding pathy's that old at local junkyards around. Even a part # would help (I don't think that's in the service manual you gave me?). I tried a search but don't seem to find a part resembling mine. Yes, that switch could have been out for a long time now, and I just never noticed it. I can't think of a time when I tried to run the rear wiper with the hatch opened. And from my tests the other day, I do recall I wasn't originally getting a good short out of it. I sprayed some electronic cleaner in there and it seemed to be working ok after that, so I thought it would be alright. I guess not, and it went bad for good this time. Maybe I can repair it once I remove the latch, but I'll have to take a look and see when I get there. 

 

Your mention of the cargo light also reminded me that I have to manually turn mine on, even when opening the whole tailgate. I would think that switch would be obvious, but I seem to recall looking for it some years ago, and not immediately finding it. If you can tell me where the tailgate switch is located, maybe I'll take a look at that too while I'm in there. I tried looking in the service manual, but didn't immediately find the physical location. It would be easier if I could do a search in that manual, and I thought Acrobat used to do an OCR recognition that would allow that, but I don't seem to have the option anymore. 

 

Back to the problem at hand- I'm looking at EL-72 which shows a test procedure for the amp. The text says "if the test lamp comes on when connected to terminal 6 and battery ground, the amp is good". But the diagram shows the test lamp connected between terminals 2 and 7. Terminal 6 they show as battery ground in that diagram, and terminal 7 is body ground according to the diagram on El-70. Do you think that's just a typo/mistake in the text description, and terminal 6 in the quote above should read terminal 2? 

Edited May 23 by Fbanks

[Slartibartfast]

I wish the service manual gave part numbers! Or at least a spotting guide for when they list different models of the same part with different torque specs.

 

I had a look at the hatch glass latch from my partsfinder ('95, same as my '93, hopefully the same as what you're working with). The bad news is that the switch is built into the plate under the latch, and the plate appears to come with the latch assembly (either 90330-41G00 or 90330-41G01 for an '87)... or would, if they weren't discontinued. The good news is that it's a very simple switch. Unless the contact fell off the plunger, or the plastic broke, I imagine it's just got some corrosion where the contact hits the body of the switch. Should be easy to inspect and clean once it's off. (After looking at it again, I would leave the adjustment bolts alone, and pull the latch and plate as a unit. Four bolts, one plug, and of course the linkage.) Clean up the contact points and the slots they go into with a small file, steel wool, a strip of sandpaper, a fiberglass pencil, something along those lines. That should bring it around. I would also check that the linkage from the latch isn't pressing on the plunger when the latch is closed, though I'd be surprised if that had somehow gone wrong.

 

The cargo light switch is built into the main hatch latch. Again, it's not replaceable on its own, though it looks like that assembly is still available (in three different variations, for some reason). If you look into the latch from the outside, where the striker goes, you'll see a big rubber chunk in there on one side. The striker is supposed to push that chunk inwards when the hatch closes, which opens the switch contacts. But it's a stupid design, and the rubber wears, and eventually it doesn't open the contacts like it's supposed to, and the cargo light starts flashing when you go over bumps. I imagine the previous owner got tired of the light show and unplugged the bastard. You may be able to clear this up by adjusting the striker. Mine has tape wrapped around the striker, which also works.

 

Again, I am assuming that your '87 is built the same as the four-doors I'm used to. Your cargo light has a three-position switch on it, right?

 

Looks like the instructions for testing the amp didn't translate well. I think they meant that grounding pin 6 (with the rest wired as shown) should make the lamp come on.

[Fbanks]

Hi again, thanks a lot for the info. I had some time today to take a further look. WRT to the cargo light, yes, there is a 3-position switch. My light stays off when in the middle position, but it turns on when I move it to the ON position. Off position also seems to work. I looked at the voltages coming in from the plug, and I believe the far left (Red/Grn) on the plug is +12V, while the middle pin is ground, and the far right pin (looking into the connector) is coming from the latch switch (red/white). When the switch is closed (rear door open), the red/white should be shorted to ground and allows the light to come on, if the switch at the lamp is in the right position. I guess my switch is stuck in the open position as I read +12v even with the rear door open , but I haven't had a chance to look at that yet.

 

I did pull the rear wiper amplifier, and I tested it according to the diagram on EL-72. I'm pretty sure I connected everything properly, but I was reading a negative ~3 volts between pins 2 and 7 (with 7 being the ground). If I did everything correctly, then I guess my amp is bad? Now the question, where to find one?

Edited May 26 by Fbanks

[Fbanks]

The part # on my unit says 28510-42G00, which looks like it's been superseded by B8510-42G85. However, I'm not showing that as available either. Anyone know a good source for really old Pathfinders? Just from Googling, it looks like this was also used on some later Terrano models as well, but I really don't even recall that model. 

[Fbanks]

I at least got the rear hatch switch working consistently now, so that's ready whenever I can get the rear wiper amplifier replaced. I started to do the rear tailgate switch as well, but i only got halfway through before it got dark. It seems a little more complicated, as it really won't come out from the outside the way the rear hatch switch does (the bolts will, but the latch assembly won't). And it seems in order to access it, you've got to remove the actuator panel as well in order to have any maneuvering room. It's only another 5 screws and another link or 2, so no biggie. I'll try to finish it tomorrow. I could definitely see some corrosion around the leads, but without being able to take it out yet, it was hard for me to see how the switch actually worked.