Dead 87 Pathy

[NoLeafClover]

Hey y'all,

 

I somewhat recently bought a 1987 Pathfinder SE with the vg30i. After running it a few hundred miles, I parked it and it died. There is no crank and it didnt show any major problems before dying besides some minor starter motor concerns.

I have already checked fuses, replaces a few relays, replaced the whole starter motor, replaced the battery, and checked most connections.

I was wondering if there are any specific known problems with these cars that would cause an issue like this, feel free to ask for clarification and give any suggestions yall know.

[adamzan]

I would check the ignition switch. They are 30+ years old now and I've seen a few of them fail.

[NoLeafClover]

10 hours ago, adamzan said:

I would check the ignition switch. They are 30+ years old now and I've seen a few of them fail.

 

I still get power to the accessories when I turn on the ignition though, so I'm not sure thats the problem.

[Slartibartfast]

Accessories coming on means you have power to the ignition switch, and the accessory contact in the switch is working. The starter contact in the switch could still be messed up.

 

Remove the steering column clamshell (carefully, they're brittle) and find the switch. It's on the ignition cylinder, opposite end from the key. It's got big exposed solder joints, so it's easy to test. Using a test light or voltmeter, check between where the black/yellow stripe wire connects to the switch and ground. You should have power there when the key is in the start position. If not, the switch is bad. Cheap part, easy to replace.

 

If that's not it, there are some other things between the switch and the starter that could be acting up. Sounds like you tried the inhibitor relay already. Is yours auto or manual? If it's manual and 4x4, there should be a rocker switch on the dash that says "interlock." This bypasses the clutch safety switch, so if that's what's failed, flipping the switch should let you start it. If it's auto, try starting it in neutral instead of park on the off chance the inhibitor switch is playing up.

 

I don't know if '87 had a car alarm or not, but that's what made the starter circuit act up on my '93.

[NoLeafClover]

On 3/1/2025 at 12:22 AM, Slartibartfast said:

Accessories coming on means you have power to the ignition switch, and the accessory contact in the switch is working. The starter contact in the switch could still be messed up.

 

Remove the steering column clamshell (carefully, they're brittle) and find the switch. It's on the ignition cylinder, opposite end from the key. It's got big exposed solder joints, so it's easy to test. Using a test light or voltmeter, check between where the black/yellow stripe wire connects to the switch and ground. You should have power there when the key is in the start position. If not, the switch is bad. Cheap part, easy to replace.

 

If that's not it, there are some other things between the switch and the starter that could be acting up. Sounds like you tried the inhibitor relay already. Is yours auto or manual? If it's manual and 4x4, there should be a rocker switch on the dash that says "interlock." This bypasses the clutch safety switch, so if that's what's failed, flipping the switch should let you start it. If it's auto, try starting it in neutral instead of park on the off chance the inhibitor switch is playing up.

 

I don't know if '87 had a car alarm or not, but that's what made the starter circuit act up on my '93.

I'll try what you mentioned, thanks. It is the 4x4 manual.

As far as I know the 87 has a car alarm, and I have heard that causes issues. What did you do to fix it on yours?

[Slartibartfast]

I removed it! The alarm was added after the truck was built, so it's pretty easy to take out, though you will have to pull some trim (and the driver's seat) to get it all. Most of it is just plugged in between things, so with it gone, the truck's harness plugs back into itself like the alarm was never there. The brain is under the driver's seat (square, white sticker on top, or a round hole with a button underneath if the sticker is gone), and its harness runs along the edge of the driver's side carpet to the A pillar, where it intercepts the power door lock wiring. Then it goes up into the column, where it intercepts the ignition switch. There are additional wires scotchlock'd into the park lights and dome light circuits, another plugged into the horn wiring, and a few wires through the firewall for the siren and the hood pin switch. These can all be cut, but if yours has fog lights, those wires are run through the firewall along with the siren wiring, so don't just chop that whole bundle.

 

If you just want to bypass the alarm's control of the starter motor, you could just bypass it at the ignition switch (unplug ignition switch from alarm harness, unplug alarm harness from main harness, plug ignition switch into main harness) and be done with it. That would also take out the alarm's power source, so it would be effectively abandoned in place. Should work just as well. I was just done with mine and wanted it all gone. (I had previously bypassed the starter kill at the alarm end of the harness, and I was still having issues, so I knew the problem had to be in the harness or its plugs.)

 

That's how it was on the four-doors I've been into. May or may not be accurate for your two-door. The service manual doesn't even mention this system, and the only service bulletin I've found that covers it (NTB93-036) only mentions '93. If it's got an aftermarket system, it's probably wired into the same things, but less delicately. If in doubt, follow black/yellow from the starter, and look for butt connectors, electrical tape, and Scotchlocks. I've got a paper copy of the '87 service manual, so let me know if you need a wiring diagram to put it right.

[FirstGenFreak]

On 3/1/2025 at 6:22 PM, Slartibartfast said:

Accessories coming on means you have power to the ignition switch, and the accessory contact in the switch is working. The starter contact in the switch could still be messed up.

 

Remove the steering column clamshell (carefully, they're brittle) and find the switch. It's on the ignition cylinder, opposite end from the key. It's got big exposed solder joints, so it's easy to test. Using a test light or voltmeter, check between where the black/yellow stripe wire connects to the switch and ground. You should have power there when the key is in the start position. If not, the switch is bad. Cheap part, easy to replace.

 

If that's not it, there are some other things between the switch and the starter that could be acting up. Sounds like you tried the inhibitor relay already. Is yours auto or manual? If it's manual and 4x4, there should be a rocker switch on the dash that says "interlock." This bypasses the clutch safety switch, so if that's what's failed, flipping the switch should let you start it. If it's auto, try starting it in neutral instead of park on the off chance the inhibitor switch is playing up.

 

I don't know if '87 had a car alarm or not, but that's what made the starter circuit act up on my '93.

I'd just pull the wire off the starter and put a test light/multimeter on there as your first check, saves pulling the shroud off the column

[NoLeafClover]

I got a bit more information over the weekend.

I tested the ignition and read a good 12.7v on the starter solder. And got the same through the battery and down the wire to the starting motor. 
I bump-started it multiple times without issue, and it ran beautifully until I shut it off.

I have bench tested the starter, so I know that runs well. The only other thing I can think of is that somewhere the signal from the ignition isnt getting to the starter, even though power from the battery is. I'll look for the car alarm system and try that soon if I can.

[Slartibartfast]

Is that 12.7 on the fat wire from the battery, or the signal wire?

 

 

[NoLeafClover]

13 hours ago, Slartibartfast said:

Is that 12.7 on the fat wire from the battery, or the signal wire?

 

 

 

Both, the fat wire from the battery gets 12.7v and the signal wire (I only tested it at the ignition, not down by the starter) is getting 12.7v

[NoLeafClover]

On 3/1/2025 at 12:22 AM, Slartibartfast said:

Accessories coming on means you have power to the ignition switch, and the accessory contact in the switch is working. The starter contact in the switch could still be messed up.

 

Remove the steering column clamshell (carefully, they're brittle) and find the switch. It's on the ignition cylinder, opposite end from the key. It's got big exposed solder joints, so it's easy to test. Using a test light or voltmeter, check between where the black/yellow stripe wire connects to the switch and ground. You should have power there when the key is in the start position. If not, the switch is bad. Cheap part, easy to replace.

 

If that's not it, there are some other things between the switch and the starter that could be acting up. Sounds like you tried the inhibitor relay already. Is yours auto or manual? If it's manual and 4x4, there should be a rocker switch on the dash that says "interlock." This bypasses the clutch safety switch, so if that's what's failed, flipping the switch should let you start it. If it's auto, try starting it in neutral instead of park on the off chance the inhibitor switch is playing up.

 

I don't know if '87 had a car alarm or not, but that's what made the starter circuit act up on my '93.

 

I tried in both postions of the interlock switch, nothing changed. What is interlock and what does it do?

[FirstGenFreak]

Is it an auto? Make sure it's in Park. 

Sounds silly but my wife has done it before. 

 

Also, check your replacement starter off the car. Just because its new, doesn't guarantee it works, especially with aftermarket parts these days. 

Edited March 4 by FirstGenFreak

[NoLeafClover]

24 minutes ago, FirstGenFreak said:

Is it an auto? Make sure it's in Park. 

Sounds silly but my wife has done it before. 

 

Also, check your replacement starter off the car. Just because its new, doesn't guarantee it works, especially with aftermarket parts these days. 

It’s the manual, I’ve already bench tested the new starter to make sure it worked and it ran.

[Slartibartfast]

8 hours ago, NoLeafClover said:

What is interlock and what does it do?

 

The interlock prevents you from starting the truck with the clutch engaged (so you don't crank it in gear and lurch into the garage door). There's an interlock relay between the switch and the starter, and it won't connect the two wires together unless the clutch switch is closed. The interlock switch on the dash bypasses the clutch switch, allowing you to start it in gear (which I'm told can be useful in some off-road situations). I suggested trying that switch in case the clutch switch was bad.

 

The black/yellow wire from the ignition switch runs to one contact in the relay. The other runs through black/pink to the starter motor. To connect the two, the relay's coil needs power from black/yellow (it just tees off from the other black/yellow, from the ignition switch) and ground from light green. Light green goes to the clutch switch, and the other side of the clutch switch is wired to a body ground. When you press the clutch, the switch grounds the relay. Then when you turn the key, the relay gets power, closes, and connects the key switch to the starter.

 

Here's what I'd do.

 

Locate the interlock relay. Oddly I don't see a relay by that name in the "location of electrical units" section, but I'm guessing it's the inhibitor relay (grey), second from the front of the line of relays behind the power steering reservoir. Should have two black/yellow wires, one black/pink wire, and one light green wire going into it. Figure out which connections go to which wires. Remove that relay and rig a test light or voltmeter between the pin wired to black/yellow (either one will do) and ground. Turn the key, and you should see power. If not, the circuit is broken between the key switch and the interlock, which is where the alarm system would be.

 

If you do get power, rig a jumper from black/yellow to black/pink (across the contacts, bypassing the relay--do not jump to the relay coil pins!), and turn the key. If the starter still doesn't turn, that suggests black/pink is broken between the relay and the starter. There are two plugs, the one at the starter and one before that somewhere, so see if you can follow that wire. Look for loose connectors, corrosion, loose wires burned through against the exhaust, that kind of thing.

 

If the starter does turn with the interlock relay bypassed, then either the relay is junk (sounds like you may have just replaced it?), or it's not getting ground on the light green wire. Light green at the relay runs to light green at the clutch switch. Black from the clutch switch goes to ground. The clutch switch should have continuity when the clutch is pressed. You could test that whole side of the circuit at once by rigging a test light between battery + and light green at the interlock relay. The light should come on when you press the clutch down. (Light green is one of the coil wires--the one that doesn't get +12v when you turn the key to start.)

 

Worth noting, the clutch and brake switches (and the cruise control cancel switches, if equipped) have stupid little rubber bungs that they hit. The bung dries out, falls out, leaves a hole where it used to be, and then the switch doesn't work right. Tends to cause the brake lights to stay on. I haven't messed with a clutch switch in one of these (mine's automatic), but I wouldn't be surprised to find a similar failure. You might even find the bung on the carpet. Replacements are cheap. I doubt this is the problem, given it still didn't start with the interlock emergency switch on the dash flipped, but it's worth a look if your fault-finding ends up pointing at the clutch switch. Hell, given its age, it's probably worth checking them anyway.