My '96 GP is starting to be an electrical nightmare!

[Brodizzle83]

So far since I bought this car about a month ago, the only issues I've had are electrical. First the sunroof wouldn't close from the vent position. Then the left turn signal blinked slower than the right, then it would work intermittently and now it won't blink at all (and the front bulb wont illuminate brighter when signaled). Then the door locks from both door switches wont work (they work on the key fob). Then my car wouldn't start so I replaced the battery (battery was 9 years old and the car starting hasn't sounded normal since I first started it for the test drive). Has anyone had gremlins like this in their 1gen Grand Prix before?

 

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[primergray]

Regarding the turn signal, you could try swapping the turn signal flasher with the hazard lights flasher and see if that fixes it.

[GTP091]

If you don't have already, get yourself a test light, a digital multimeter, and a Haynes/Clymer  book and go at it. 

 

Your car is a bit more corroded in places than some.  It's very likely that some of these issues, maybe even all of them are related to bad grounds which is any easy fix.  Any electrical troubleshooting guide no matter what it is, tells you to check the fuses, then check the grounds, test for power, test the component/light works with a standalone power source.  I hope it goes without saying that when you test circuits you have to close the circuit (press the button, turn the knob, flip the switch) . In my experience electrical issues are almost always ground problems and testing with a digital multimeter on the ohm selector is how you test an open circuit.  It's better to have a bad ground than a fuse that pops randomly, if its the fuse then you have a short/bare wire somewhere in the circuit and they're a bugger to find.  Bad grounds are easy to fix up, you just have to find them, clean them, and put back together. If you see a connection with green crud or white fuzzy stuff clean it well with a very fine small brass wire brush (hobby type) and coat the connector in dielectric grease.

 

It's very unlikely that you have an open circuit somewhere in the wire loom inside the vehicle as its taped up and protected very well from the factory.  Unless someone has gone cutting and splicing especially under the dash your probably not going to find a cut wire (open circuit) on the interior. 

 

Under the hood is another story, it's hot, gets wet, people over the years tug and pull on wires, move stuff out of the way to service the engine etc.  Most of what's under there is engine sensors, ignition, and injection wires so most of the small random wire looms you see going everywhere wont be the issue.  You do have a fuse box under there that powers the engine electrical systems; the outgoing terminals could be corroded and needing attention.  The wire looms for the headlights and the signals are all very easy to get at. Somewhere in the system your likely to find some corrosion, even in the light socket.  I believe the ground for the signals is on the drivers side behind the headlight close to the horns.  Based on the condition of your battery tray you should take a look at these grounds.  But first as already suggested try a new flasher. 

 

The sunroof issue is likely a ground problem.  You tested the motor as working (replaced it?). Next is test that there's power getting to the motor with the test light. if there is keep checking all the way to the ground; after the motor, before the switch, after the switch this will show you where the open circuit is and you fix it from there.  

[Schurkey]

the left turn signal blinked slower than the right, then it would work intermittently and now it won't blink at all (and the front bulb wont illuminate brighter when signaled

Have you replaced that front bulb?

 

First Guess:  One filament burned out.

[Brodizzle83]

Have you replaced that front bulb?

 

First Guess: One filament burned out.

I checked the bulb...it is not burned out.

 

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[Brodizzle83]

Regarding the turn signal, you could try swapping the turn signal flasher with the hazard lights flasher and see if that fixes it.

I did that and neither side blinked. I will get a new one tomorrow and see if that works.

 

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[Galaxie500XL]

The turn signal switches in these cars are notorious for failure...I replaced two in the 7 years I owned my Cutlass, and the switch was beginning to fall when I sold it.

[Brodizzle83]

The turn signal switches in these cars are notorious for failure...I replaced two in the 7 years I owned my Cutlass, and the switch was beginning to fall when I sold it.

I believe the car came with a brand new one. I'm not sure how difficult it is to install...I'll have to look in my factory service manual.

 

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[mfewtrail]

I checked the bulb...it is not burned out.

 

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Just for future reference, it's possible to have an intact filament but still have a bulb that doesn't work.  I run into this occasionally where there's obviously a bad connection in the base of the bulb. This might not be your problem, but could be helpful to you in the future.

[Imp558]

Just for future reference, it's possible to have an intact filament but still have a bulb that doesn't work. I run into this occasionally where there's obviously a bad connection in the base of the bulb. This might not be your problem, but could be helpful to you in the future.

Could swap them left to right. In the 1996 Regal the side markers are in the circuit with the front markers. I imagine the GP is similar so maybe make sure something isn't funky somewhere else up front.

[Brodizzle83]

So the bulb was bad (replaced both sides) but the left bulb blinks slower than the right. I haven't replaced the flasher yet...gonna so that today.

 

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[rich_e777]

Replace the front ones to, front right and rear right as a pair, front left rear left as a pair. Use the $1.29 packet of bulb grease too, it works. The larger dual filament bulbs are probably 3157s or 3057s(both fit the same socket) and if you have small front corner ones like the Cutlass Supremes do IIRC its 194s or maybe even tinier 64s?

[Imp558]

the left bulb blinks slower than the right

 

The slow side has a bulb out somewhere the blink rate is proportionate to current draw.

[Brodizzle83]

The slow side has a bulb out somewhere the blink rate is proportionate to current draw.

Ah, good to know. Are there 2 or 3 bulbs in the rear turn signals? I checked them last night and I believe I saw that both L and R rear turn signals had 2 bulbs and all of them illuminated.

 

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[Imp558]

Hit the four way flashers and you'll be able to see what's different between the two sides.

There could potentially be a poopy ground too.

Edited June 2, 2018 by Imp558

[Brodizzle83]

Hit the four way flashers and you'll be able to see what's different between the two sides.

There could potentially be a poopy ground too.

Yeah none of the rear bulbs are out. Its strange...

 

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[GTP091]

You could always try an electronic flasher.  I lucked out and found one of these in the JY, hardly paid anything for it; otherwise they're about $15 new.  It does not use the resisitance of the circuit to control its rate output so is used on LED changeovers.  This flasher will not let you know when you have a burnt out bulb so you will need to do burnt bulb checks to keep your car legal and safe.  Doing this is a band aid solution though, it would not help resolve the original issue you have.

 

In my experience when a bulb is out you get hyperflashing (faster flashing) not a slow flash.  Are you sure you're not mistaking the left slow flash for a normal rate and the right faster flash as an indication of a burnt out bulb?  The rear turn signals have two bulbs each, you'll have  a single front turn signal/marker and a side turn signal on both side of the car.  Might be a good measure to change all of the bulbs just to be sure before you tear into wiring.