Where is the ground pt inside a '96 GA?

[syc0path]

I'm having some electrical problems in my gf's '96 GASE... the DRLs don't come on so the high beam indicator flashes all the time, the auto headlights don't work (if the car even has auto headlights!), the washer pump doesn't work (even though it works if u feed it power directly from the battery), sometimes the wipers only work on high, etc.

Anyway, I have part of a service manual and it has wiring diagrams. I did some testing w/ a voltmeter on the DRL circuit and everything works -- except 1 wire that doesn't ground when it's supposed to.

Turns out the ground for this wire is shared by many other components, including the wiper motor:

Radio
Steering wheel controls
Ignition switch
Wiper motor assembly
Ignition lock solenoid
Convenience Center/Multi-function alarm module
Instrument panel cluster microprocessor (this controls the DRLs)
Data link connector
Instrument panel compartment lamp
PRNDL control module
BTSI shift lock
Fog lamp switch
Rear defogger switch
Cigarette lighter
Panel switch dimmer
Enhanced traction control switch

So I wanna check to see if the ground is rusted, corroded, etc. The problem is, we can't find it! My dad even checked out a car in the junkyard that had most of the interior removed and he still couldn't find it. Does any1 know where it is??

1 more question -- the manual shows that this car should have auto headlights. But they've never worked and I can't find the photosensor. It's always in the top center of the dash on other GM cars, but it's not there. Is that where it should be?

[arthurgoboom]

The sensor should be under the windshield defroster vent, it's biased a little towards the passenger side, but still in the center 1/3 of the car.

As for the ground, I'm not sure. I know on mine there are 2 ground points on the driver's side fender, right up near the hood edge, and another one on the firewall around the brake booster area. I'm not sure if any of those are the grounds you're looking for, but I'm thinking what you're looking for is inside the car somewhere. If you have found the wire that isn't grounding, couldn't you just snip it off and run a new ground wire to a ground point in the engine compartment?

[syc0path]

The sensor should be under the windshield defroster vent, it's biased a little towards the passenger side, but still in the center 1/3 of the car.

As for the ground, I'm not sure. I know on mine there are 2 ground points on the driver's side fender, right up near the hood edge, and another one on the firewall around the brake booster area. I'm not sure if any of those are the grounds you're looking for, but I'm thinking what you're looking for is inside the car somewhere. If you have found the wire that isn't grounding, couldn't you just snip it off and run a new ground wire to a ground point in the engine compartment?Oh... so if that sensor is under the vent, it wouldn't be very visible unless u knew where to look for it. I'll check that out tonight -- thanx for the tip!

Yeah I know the 2 ground pts on the fender u'r talking about -- I pulled those apart a couple months ago when I was trying to fix the washer pump problem. I hit them w/ a wire brush to knock off all the corrosion and coated them w/ anti-seize. So those should be good to go, although I suppose it couldn't hurt to check them again. But I don't think I saw the ground on the firewall... I'll check that out tonight too. I does seem like the ground pt should be inside the car, but I heard that it's actually under the hood in the '98+ models... maybe it was the same w/ the '96s too.

The wire for the DRLs that doesn't work is supposed to provide a ground for the trigger circuit for the DRL relay. That ground is supposed to be switched on and off by the microprocessor when the car is running or not. The microprocessor is in turn grounded to the ground pt I'm looking for.

[rixGAphx]

Antiseize is a kind of grease, and it is an electrical INSULATOR.

There is a special product called Di-Electric grease to use between two different metals that carry electricity.
* * *
Think of how this car was assembled: The dashboard, complete, was fabricated over there in Plant 1 (might even be in a different continent) then delivered to the body assembly line.
It was dropped down through the open windshield and fastened into the car.
It has as FEW wires as possible for 'final connection', and of necessity *most* are over at the driver side, for connection of/to the ignition switch (in the steering column for your year) and the fuse box (in the left end of the dash) and the unswitched power supply into the lighting (from the load center, next to the mastercylinder).

That's where I would put the ground that picked-up the ground from all those other in-dash systems to connect to the firewall.
Prolly the best place to look.

[syc0path]

Antiseize is a kind of grease, and it is an electrical INSULATOR.

That's where I would put the ground that picked-up the ground from all those other in-dash systems to connect to the firewall.
Prolly the best place to look.That's a good pt about anti-seize, and I should clarify what I meant. I took the connections apart, cleaned the corrosion, and put them back together. Then I "painted" the anti-seize over the top of the connection to prevent salt, moisture, etc from getting in. But the actual connection between the ground tab on the end of the wire and the sheet metal of the body is making direct metal-to-metal contact.

So are u saying the ground would be on the firewall inside the car or outside? I cleaned the firewall ground in the engine compartment last night, but it didn't fix anything. I also found the photosensor... at least I think I did. There's a black plastic disc about 1" in diameter on the far pass side of the defroster vent. There's a little hole in the center and that's where the photosensor should be.

So it looks like this car does have auto headlights... last night as I was working on it, it was starting to get dark. I started the car and the headlights were dark -- not even the DRLs were on. Instead, only the parking and foglights came on. There was no way to turn the parking lights off and I had to use the switch to turn the headlights on. So I hope this is also being caused by a bad ground.

[syc0path]

Well I as I was messing w/ it, I turned the ignition on and noticed that, when all the idiot lights come on, the brake light was flickering. Then I remembered that setting the parking brake would make the DRLs shut off. So I thought maybe there was a weak ground that could be causing the problem. I took the center console apart, but the wiring looked fine. I did some testing w/ it and still couldn't get the DRLs to come on. We finally determined that the flickering brake light was caused by a loose sensor connection on the master cylinder and had nothing to do w/ the parking brake.

So at this pt, it looks like we're down to 3 options -- a ground inside the car that we haven't found yet (if there is 1!), a bad photosensor, or a bad microprocessor.

[syc0path]

My dad's friend came over last night... he works at GM and has a Tech II scanner/programmer. So using the Tech II, we were able to command the DRLs to come on whenever we wanted. That made it ezr to track down exactly where the problem was.

Turns out there was a break in the orange wire that supplies power to the DRL relay. The orange wire splits to 2 other orange wires up near the relays in the front bumper (I believe the 2nd orange wire powers the auto headlights relay). Well that connection is not sealed very well and there was a lot of corrosion inside. It was good enough that I got a reading of 12V w/ the voltmeter, but not good enough to actually power the DRLs. So that should fix it... we tested it w/ a jumper wire and it worked properly. But it was getting dark so we didn't have time to fix it for real.

[rixGAphx]

Great!

Thanks for reporting back, might help somebody else in the future.

[syc0path]

We put it all back together and tested it last night -- it works fine and the auto headlights work too :) Now if I can just figure out the wiper...