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Can someone out there talk to me about 1)  the Resistor and condenser (105E) located in the Engine Control Harness (Page EL-101 of the Service Manual).  Mine has melted exposing two connections; one broken completely, but doesn't seem to be effect anything.  I'd love to replace the unit if I could only find one or somebody who knows a work-a-round.  2)  Also the Pressure Relief Value, located on the end of the high flexible hose near the compressor has ruptured.  Can it be replaced or do I have to get a complete high flexible hose assembly?

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Further to my post of August 14:

I believe I've solved 2) the AC Pressure Relief Valve problem for the present.  Nissan response is it's not a serviceable part; not a big surprise, in that it's an old R12 system.  Nissan also said the complete high hose assembly is not available either.  I found that an available R134 AC Pressure Release Valve for the 300ZX fits just fine in my 1990 Pathfinder High Flex Hose.  I've recharged my converted R12 to R134 AC system and now produce 40 Degree F and the center vent once again.  I'm told the new valve will reset in the event it blows again.

 

I'm still researching the Resistor and Condenser (105E) located in the Engine Control Harness.  It is a tested component of the Ignition Signal (Code No. 21) Diagnostic Procedure 6 (Pages EF & EC-100 to 102 and EF & EC-152).  The four-pronged resistor is supposedly replaceable.  I need to replace the harness connector as well since the whole thing has melted into an unrecognizable blob.  I really need to contact a veteran Nissan technician for some guidance.  I haven't found any help other than those who have suggested go to Pick-N-Pull and cut the thing out of a similar vintage Nissan with a VG30E.

 

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Sorry it took a while to reply to this one! Took me a little head-scratching.

Best I can find as far as components is a rating of 2.2k ohms for that resistor (marked in the full wiring diagram of the '95 manual). The resistor's between switched ground to the coil and the ECU, so I suspect the ECU's using that circuit to monitor switched power to the coil, and the resistor limits that current to protect the ECU. I see no spec for the condenser, which looks like it's just there to muffle the electrical noise the coil wants to spit back into the electrical system.


Electrical plugs can heat up and melt themselves if they get corroded inside (the corrosion adds resistance, resistance with current across it makes heat), but that requires current. Looking at the diagram, neither component should've been passing anywhere near enough current to let the smoke out. The condenser has 12v from the key switch on one side and ground on the other, so if that condenser shorted out somehow, or corrosion shorted it out in the plug, that right there would definitely let some smoke out, right up until the connection got so hot it burned through. Hopefully the plug and the module are the only casualties and the wires feeding it didn't fry, too.

Wreckers would be my first thought too, but failing that, 2.2k resistors aren't hard to find. Sucks not knowing what the value is on the condenser. I've got a meter with a capacitance setting, I'll have a look at mine see if I can figure out what value it's supposed to be.

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Thanks Slartibartfast for the post.  I see that you have a 1993 SE but referenced the '95 FSM.  Are the '90 thru '95 SE and FSMs the same or nearly so?  I've got a '90 FSM if you're interested. 

 

As ugly as the thing looks, it doesn't seem to be affecting anything. Although I'm consistently getting a Trouble Code 34 with no CEL even after replacing the Knock Sensor with a Hitachi OEM part.  I got rid of a Trouble Code 51 by replacing all the Injectors and the old VG30E is running great right now.  I've yet to get a Trouble Code 21.  I'd like to repair the Resistor & Condenser unit in the harness to see if that magically makes the Code 34 go away.  I don''t relish the idea of chasing the harness all the way down under to the new Knock Sensor.

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I've got a few manuals on here, including the '90 (thanks though!), but for some reason it's missing the wiring foldout that the later manuals came with. A few little things changed here and there just to be unhelpful, but yeah, most of the info is the same 90-95.


Thinking about it, I wouldn't be surprised if fixing this module made the knock code go away. The condenser's job is to filter out the noise made by the coil, and the knock sensor's basically a microphone feeding noise to the ECU. What do you want to bet the coil noise is getting picked up by the ECU and interpreted as abnormal knock sensor noise?

I didn't get to checking mine today, but I'll have a look tomorrow and see if I can work out what's inside!

 

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Thanks. I really appreciate your help.  That wiring foldout is a real challenge.  I have to project it onto my bedroom wall in order to see it completely & clearly.  I wonder if the image could be converted to a large blueprint?  I just tried to upload an acrobat.pdf of the 1990 Circuit Diagram (p 1529) only.  It's too big.

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Yeah, definitely some zoom needed on that one! Thanks for trying to upload, not surprising it wouldn't go though.

 

I had a look at mine today. The end of the module actually has the component ratings marked on it! The condenser (aka capacitor) is 2.2 microfarads, 50v, and the resistor is 2.2k ohms, 1/2 watt. It's also marked 8115 in white paint for some reason (probably a batch number or something). I wasn't entirely sure how it was supposed to come apart and decided I didn't want it apart bad enough to risk breaking it.

EF&EC-10 of the '90 manual has the color codes for the wiring. Looks like the resistor goes between blue and white with a green stripe, and the cap goes between black with a white stripe and black. If the replacement cap is polarized, make sure you hook it up the right way around (black is ground).

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Thanks.  I found a less busy diagram on EF&EC-100 with the same info you describe.  Also an image of the "replaceable" Resistor/Condenser plug can be found on EF&EC-152.  Diagnostic Procedure 6 for Ignition Signal (Code No. 21) asks to check for continuity from the Harness Side (H.S.) of the 105E Connector, while also checking for resistance between terminals (a) and (b) of the Resistor plug without clearly identifying which terminals are (a) and (b).  Of course I can't test anything since the four-terminal Resistor/Condenser plug and harness connector are a single melted blob on the end of four wires.  I'm going to inspect the blob more closely with some magnification to see if I can determined which wire is broken completely.  L = Blue, B/W = Black w/White Stripe, B = Black, W/G = White w/Green Stripe.  Do you suppose I can manufacture these items separately.  I think I might be able to fit some butt connectors with the available wires.  Might even need to split open the harness from which the blob is protruding.  I've got a lot of left over wiring loom from other jobs.  I've got a lot of old, and new, radio controls (transmitters and receivers) used in the garage door opener and automatic gate opener business.  I wonder if these particular resistors and/or condensers/capacitors might be found on a radio control circuit board? 

Edited by SkipHarrah
spelling and additional content

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That one's a little easier to read!

I've scavenged a lot of components from old electronics, but given how cheap these components are new, I'd save myself the hassle and just order new ones. Used caps are kind of a crapshoot and the short leads left over on salvaged components can be a pain to work with. Also, most resistors I've found in stuff I've taken apart are quarter-watt, so you might have some trouble find the half-watt spec'd on the case. If you want to dig through what you've got, start with the older stuff, it's more likely to have through-hole components.

I'd just cut off the blob and solder the new components to the wires. Hopefully there's enough wire to work with without having to unwrap the injector harness. If you're buying a capacitor, I'd look for an axial capacitor (one lead coming out of either end of the can), just so it's easier to solder/shrink wrap in line than the usual radial cap (two leads out the bottom) would be. I like the shrink wrap with adhesive in it (won't slide off and water can't get in). Basically you'll have two loops where the blob was, one with a resistor and one with a cap, and then you can just wrap the whole mess in tape and either tape it or zip tie it back to the harness so it doesn't bounce around.

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Wow...Thanks for the post.  Where should I shop for new stuff?  Fry's maybe?  The 8115 code you found on the end of the module looks very much like a manufacturing date format used by early garage door operator makers, i.e. 15th week of 1981.  I looked at my blob closer today and found it's the (B) - Black wire that is completely detached from the plug-in module (the terminal is gone) but still attached to the harness side of the blob.  The Black wire appears to remain intact all the way to the Distributor grounding point (56M) via 101E 70M.  My circuit tester lit up by clipping the exposed piece on the harness blob and touching the battery positive terminal.  Got the same response by clipping the exposed B/W wire also.  Can't figure out how it is reaching ground that way (through Ignition Coil maybe?).

Edited by SkipHarrah
Wire ID correction.

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I usually order off Amazon/eBay, or Digikey if it's something more specialized, mostly because there's no brick and mortar near me that sells this stuff. Fry's looks like a good bet if there's one near you.

Interesting if that's a date code. That would suggest Nissan ordered a whole bunch of these things for an earlier model and had enough some left over to last them at least until '93. Might explain why the plug doesn't look like any of the others.

Good to hear the wiring's okay. I'm guessing the other one you tested was the black/white? That wire goes to the ignition switch and tees into a whole lot of other things that also run to the ignition switch, and all of those things are grounded somewhere. Your ground might be through the blower motor, the radio, the ECU, or any of the other stuff on that circuit.

I had a run-in with that kind of thing on my '95. It had a door switch for the tire carrier, and an idiot light for when I left it open, so I rewired it to turn on the cargo light when the carrier was open. Everything seemed fine until I turned the key off and the idiot light came on! The cluster (which was + when the key was on) was grounding somewhere, and the cargo light was hooked to constant +, so current was backfeeding through the bulb. Once I finally figured out what was going on, I added a diode to the circuit and it stopped doing that.

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Amazon yes: I found a single 2.2 uF 50V 20% Nonpolarized Electrolytic Capacitor 9000Hz for $5.00  and two different 2.2K ohm 1/2W 5% Carbon Film Resistors; a 5-pk w/longer leads for $10.46 and a 10-pk w/0.028 in (0.70 mm) leads for $5.78.  Resistors seem to be more plentiful than Condensers/Capacitors.  I didn't find a polarized capacitor at all.  I'm an Amazon regular and saved a number of items in my private shopping list.

 

I thought of using the Solder Seal Wire Heat Shrink Butt Connectors for install.

 

Yes; I corrected the second wire tested to the B/W.  Further testing today I learned that the B/W goes hot when the Ignition Switch is turned ON; which means 12V would be going through the condenser/capacitor to the B wire to ground at the Distributor.  Does that make sense?  I wasn't expecting that.  My original 1990 Ignition Key Switch and Inhibitor Switch were replaced in 2002.  I wonder if that is when the thing melted.

 

The B/W wire goes only to the Coil and branches through the knock sensor connector (102E)<->(71M) main harness connector then to the Ignition Switch (221M).  I checked for continuity on the B wire and got 0.8 (or 0.003) ohm reading.  Continuity for the larger B/W wire tested 7.3 (or 0.013) ohms.  Would that be because it's a thicker wire or a problem at the Ignition Switch?

 

 

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Those connectors look interesting, though I'd expect them to work better on new wire than old, possibly corroded stuff that can be a pain to tin even when doing it normally, and I'd still want to shrink-wrap the components themselves to keep water out. Let me know how it goes if you try them, I've read about them but haven't tried them myself.

Non-polarized means you can't hook it up backwards, so that's nice!

 

Hooking up a cap like that is a very common way to deal with noise. Current flows until the cap has charged to the same voltage as the circuit it's connected across, and then it stops. If the voltage rises, the cap draws power until it's charged to match; if the voltage drops, the cap discharges back into the circuit until it matches. So if the voltage is fluctuating, the cap will smooth it out, blunting the peaks and filling the valleys. If the voltage is constant, and the cap is charged, no current should flow through it.

I don't think a failure of the ignition switch would've damaged the cap. More likely your ignition was replaced due to the usual click/no-start of worn-out starter contacts, and the cap failure is unusual but unrelated. (Did the PO of yours bother to have the key matched to the doors? The PO of mine didn't, annoyingly.)

The + connection on the ignition switch that the b/w wire eventually finds its way back to is shared by many other things (the other things that come on when you turn the key). I'm a little confused by your units (different scales?) but it makes sense that the wire going straight to ground would have bugger-all resistance, and the wire going to positive and grounding through various other things might have slightly more. If your meter shows battery voltage across the cap (between b/w and b) when the key is on, I wouldn't worry about it.

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I just got my supply of Resistors thru Amazon.  I ordered the 2.2K ohm 1/2W 5% Carbon Film Resistor 5-pack.  It appears I got 10% tolerance instead, judging by the Silver band on the end.  Would that make a difference in my application?

 

I'm still waiting on the Capacitor which is coming separately from another supplier.

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That's annoying. I doubt the circuit will notice or care, but if you've got a meter handy, you could check the five resistors and use the one closest to spec.

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Now, I'm getting confused.  Tested all five several times. Got readings of 1.622 through 1.629 initially. Put fresh batteries in my Multimeter, then got readings of 1.653 through 1.657. 

 

Color band codes on the resistors (red, red, red) indicate 2200 ohms with silver band (10%) tolerance.  The RadioShack package label reads "Carbon Film Resistor 2.2K-Ohm 1/2-Watt 5% tolerance".  You think I should try again from somebody else?

 

P.S. Never mind. I learned how to set my Multimeter correctly. New readings run from 2.165 to 2.176.  So we're good.

 

P.P.S. Just got the Capacitors. Another RadioShack item. I'm worrying a bit about the stated Operating Temp of -40F to +185F.  The low side is not an issue, but the high side at 185F sitting on top of the WG30E seems to be pushing the limit.  The Resistor packaging does not provide an Operating Temp range.  I don't think RadioShack anticipates using these products on things other than radio equipment, e.g. the caps are spec'd for speaker crossover: 8kHz at 8 ohms.

Edited by SkipHarrah
additional content; post script

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Hmm. Didn't think about heat rating for the cap. I'd be curious to see how hot that section of harness actually gets. It's not bathed in coolant or buried so I wouldn't expect it to reach the operating temp of the engine. Looks like caps are available in a 105°C (221°F) flavor if you'd rather play it safe.

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I'll give these a shot, since I've got no cap at the moment  I got these two caps @ $5 a piece.  I can keep an eye on both the cap and resistor where they are located.  I also noticed (by testing with the multimeter) that there is clearly a positive and negative side of this particular "non-polarized" cap. I'll mount the neg side to the black wire and pos side to the black w/white stripe wire just for good measure. Might be able to salvage the socket side of the blob, we'll see. This will be my project for the day.  I'll post my results when I have some.

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Well I got the missing/burnt capacitor/condenser piece installed well enough to do further testing.  I left the resistor piece alone (other than removing and cleaning) since it tested just fine.

The Code 34 continued to show up as before. Also I began getting a Code 51 immediately.  Subsequently found out that the connector on newly installed #6 injector had worked it's way loose, bad clip job.  We also have learned the shielded wire going to the knock sensor has become compromised/broken midway from the knock sensor connector (111E) and Engine Control Harness Connector (102E).  The rest of the harness and connectors are in reasonably good shape.  We are currently searching for replacement shielded wire for the knock sensor.

 

Does anybody have a spec on that shielded wire?  And a place to get it other than the wrecking yard.  I have a bunch of heavy duty shielded audio/speaker cables.

Why wouldn't that work in this application?

 

Edited by SkipHarrah
additional content and follow-up question

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Too bad the cap didn't do anything to the code, but good work finding the actual cause!

The audio cable would probably work fine, provided you can ground the shield, but there's probably an easier and cleaner way. If the mushed section isn't too bad, I'd be tempted to repair the wires, pull the shield back over if it's not completely severed, and heatshrink it all down. Looks like you can also get wire shielding tube on its own in various sizes to go over whatever wire you want to use.

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Thanks for the post.  I'll go over the details with my mechanic in the morning. I'll post results when I have some.

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I found upgraded Knock Sensor wire (shielded single conductor) from Z1 Motorsports. My mechanic installed the new wire from Knock Sensor connector 111E all the way to Engine Control Harness connector 102E, repaired the bad clip job on Injector No 6 connector 113E, and did a beautiful job of adding new wiring loom to the old Engine Control Harness.  He left my temporary Condenser replacement as is.

 

The old 1990 SE ran beautifully when I picked it up and the first five miles of my six-mile trip home.  It lost power, belched white smoke out the tail pipe and died on a steep grade approaching home.  I was able to roll backwards down the hill into a neighbors driveway.  Upon lifting the hood I could see a portion of the main harness smoking.  It was later determined to be the black wire to the distributor ground 56M that originates at the Condenser 105E via 70M/101E connector.  I'm in the process dissecting burnt/melted harness and restoring/rebuilding one wire at a time.  I'm hoping to get a new OEM Engine Control Harness from MegaZip's Japanese Warehouse, but it's beginning to look iffy.  Ordered/Paid on Oct 5th and hasn't ship yet.  I'm expecting to get word they can't deliver, just like all the other Nissan parts distributors I've contacted.  Next stop will be the wrecking yards I suppose.

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