turn signal gremlins

[woody90gtz]

This is the only thing keeping from passing NYS inspection, so I need to remedy it asap. Symptoms:

The right turn signal works correctly. The left turn signal flashes all the bulbs, even the license plate - and both indicators on the cluster light up solid. The left indicator also lights up solid whenever the head lights are switch on. It sounds like a ground feedback problem, but I havent found it yet.

The hazards flash the unused base 194 bulbs, not the side markers like they should - I wondered if I could splice the feed for those bulbs to the side markers without causing more issues.

A 91 GTZ light harness would be the ultimate fix, if anyone has one kicking around. Otherwise I still need to wire the fogs as well. If some one can let me know the color of the fog light wire from the headlight switch I can take it from there.

Thanks!

[3X00-Modified]

How do you think a GTZ harness will fix your rear license plate bulbs blinking? Have you disconnected the front harness and then the rears apear to work as they should? Obviously no blinking because they dont have enough load, but they light up just left and just right?

Sounds like you have one hack job of wiring back there...

[woody90gtz]

It is my belief that there is a ground screwed up in the front wiring harness that is back feeding to all the bulbs. Everything works perfect in the rear except for the left turn signal. I had a spare tail light harness and it does the same thing - and both are unmolested. The front has been spliced in a couple spots and I think that's what's giving me issues.

The right signal works fine. Just the signals blink and the dash indicator also blinks. When I turn on the headlights, only the left indicator lights up.

Then, the only other issue is the hazards blinking the should-be-unused 194 bulbs from the GT-style bumper instead of the side markers.

[3X00-Modified]

It is my belief that there is a ground screwed up in the front wiring harness that is back feeding to all the bulbs. Everything works perfect in the rear except for the left turn signal. I had a spare tail light harness and it does the same thing - and both are unmolested. The front has been spliced in a couple spots and I think that's what's giving me issues.

The right signal works fine. Just the signals blink and the dash indicator also blinks. When I turn on the headlights, only the left indicator lights up.

Then, the only other issue is the hazards blinking the should-be-unused 194 bulbs from the GT-style bumper instead of the side markers.

Well, yes replace your front harness then... Sounds like you could trace all the wires back, but I don't know what was done to even tell you where to start. First things first, you dont even need the 194's in the socket... everything will work without those even plugged in. So if they are blinking then someone spliced them into the turn circuit when they should really only be part of the parking light circuit. That may be your whole issue.

I attached a 1996 exterior lights diagram, I can only assume it was very close if not exactly the same as the 91 since the lights up front never changed.

Just look at how simple the "extra" 194's are wired in, so if they were crossed or spliced differently for god who knows what reason then those could be shorting between the park circuit and the turn circuit, hence the blinking license plate light...

[wicked-irocz]

I would attemp disconnecting the turn signal switch and trying a new one just to eliminate it as the culprit.

[3X00-Modified]

I would attemp disconnecting the turn signal switch and trying a new one just to eliminate it as the culprit.

Turn signal switch never touches the parking light circuit... thats directly wired to the switch, so if he has lights that should be functioning as parking lights ONLY and they are blinking, then I'm willing to bet those bulbs are spliced in wrong somewhere, or double spliced...

[woody90gtz]

Thanks for the diagram, that helps immensely.

I have to look at it again to be sure, but I believe they only blink with the hazards... which would be correct. But the side markers should also blink with the hazards and they dont.

From the diagram it looks like the parking circuit is grounding through the L turn signal circuit and that's why I get the light at the dash. It would also make sense why the signal circuit (lt blue) would ground through the parking light circuit (brn) without a good ground. I know that ground wire is hooked up, but maybe the wire itself is broken some where.

Edit: now it makes sense why the hazards dont blink the sidemarkers too! The juice has to feed one way or the other and with the hazards it would be getting juice from both directions without that ground.

[3X00-Modified]

Your two base 194 front bulbs should not be blinking with the hazzards... When the hazzards are put on the only bulbs that should blink are the main blinker's and the two corner bulbs, as you can see the 194's are only connected to the parking circuit and ground... where the side markers are hooked up to the parking circuit and the turn circuit.

My guess is the turn circuit when NOT engaged acts as a ground, that is why the side markers come on with the parking lights, then when they are turned on that makes the side markers blink opposite of the turn signal since it alternates from ground to 12v. But I'm not sure, its kinda odd how they have it wired and how it doesn't back feed somehow.

[woody90gtz]

Ok, I tested my own ground straight from the bulb socket to the battery and there was no change. I disconnected that 8" piece of the harness for that bulb and everything else worked correctly. I looked at the bulb itself while it was plugged in and when flashing with the signal and only one filament lights up. If it was back feeding both filaments would light. That makes me think it's the socket itself that has issues. I inspected it and it looks fine, but it has to be the root of the problem.

[3X00-Modified]

Ok, I tested my own ground straight from the bulb socket to the battery and there was no change. I disconnected that 8" piece of the harness for that bulb and everything else worked correctly. I looked at the bulb itself while it was plugged in and when flashing with the signal and only one filament lights up. If it was back feeding both filaments would light. That makes me think it's the socket itself that has issues. I inspected it and it looks fine, but it has to be the root of the problem.

That doesn't necessarily mean that the rest is fine... Check those two extra 194's and make sure they are wired in properly... if that means pulling back the wire loom and pulling off all the electrical tape, do it... I've done that to a fair share of harnesses and honestly its not that bad.

By removing that one socket you also isolated a possible improper connection to that side as well.

This front harness should be extremely simple to trace and rewire from scratch to find the issue.

I'm really pushing those 194's because of the way you said they are working, because they shouldn't work like that.

[woody90gtz]

Fixed!

I made my own ground straight to the battery and it didnt change, took the bulb out and it didnt change, disconnected that 3-wire harness for that bulb and it fixed it. So I took all the goop out of the socket and saw a little connection foot stuck between the terminals. So apparently when a bulb was twisted out of the socket, the foot broke off and was lodged in there, connecting the signal and park circuits.

Something so simple...