so guys bought another car a 1987 z28, car has few problems but im taking my time, the newest problem is that when I hit the hrake pedal the gauge lights and parking lights come on along with the "you left your lights on chime", whats wrong here ,all lights work, all fuses replaced any ideas???
thanks
sam

 

Could be something else, but I've seen cars with ground problems act this way. When a circuit can't find a good ground, it will back track through other circuits to find one.

Do you have a manual that shows the ground locations for your car?

 

Good to hear from you Dave! I was thinking its ground to and I don't have my Haynes manual anymore got wet and destroyed so I'm thinking when I get off work attack everything with the test light l just dont know where the problem could be,my other car has never had any wiring problems as strange as this,I'm trying to figure at what point the gage lights parking lights and tail lights are connected see where there ground is...but I just don't know
😤😤😤

 

Hey Sam!

I don't have any '87 manuals either. Hopefully some others will chime in.

 

Hopefully I'm driving it next week so I hope I can get it fixed

 

+1 on a bad ground. You can test this by grounding the black wire in the connector inside the drivers side quarter panel. May also want to check the contacts for third brake light on the hatch being clean and getting good contact.

 

another on a bad ground. I wouldn't test with a test light honestly. The reason i say that is there are some components on the car that are sensitive to higher voltages. I would use a dvom but yes i would check for a bad ground or a wire that is nicked or cut and grounding somewhere

 

So everyone's agreeing somethings groudning that's shouldn't be or there is no ground?

 

There is definitely a ground or it wouldn't work at all. it works, not properly, but it works. it sounds like it grounding somewhere else in the circuit

 

It's not getting a GOOD ground where it is supposed to. That's why other things, that shouldn't be, are lighting up. The current is looking for a ground. When it can't get it in it's own circuit, it looks for it by back feeding through other circuits.

 

Don't know if this will help. I tried to get photos of all of the 8A pages related to stop lamps (for my 88 T/A, from the '88 Pontiac FSM). But only this one would focus. It's probably the only one that matters. The others are showing you that the stop lamps ground at the back of the car through G303, and that it's shared with some other lamps. And, this photo/page tells you that G303 is at the "center of end panel". I take that to be behind the tail lamps themselves.



And the photo is upside down. Just not my night. Looks fine on my PC and on Photobucket.

 

see if that helps and if not then try to find a circuit in the brake lamp system that has a solder point where all the symptoms are joined and see if there is a break either before that or after that point that would cause all that to happen. I can look to see what I can find. I have access to AllData and i will look to see what i can find for you.

 

does you car have the 5.7 or the 5.0??

 

anything that is either "S", "C", or "G". if it is 100-199 then it is in the engine bay, 200-299 under the dash, 300-399 in the passenger area, and 400-499 is in the rear of the car.

 

88camaroiroc it's a 5.0 carbureted car couldn't find broke ground wire so I may just redo all the grounds tonight after work, could the problem possibly be the brake switch on the pedal? When I disconnect that the gage and parking lights stop but so do the brake lights lol I don't know what's wrong

 

Thanks for your help so far again Dave! Hope I can get this figured out tonight I'll let you guys know!

 

Its very possible. have you disconnected anything else in the circuit to see if it still does the same thing. Find a connetor before that and unplung that one and see if it fixes it. If not then find a connector after that switch and see if that fixes the issue if it does then the brake switch would be your issue. I don't think they are much it would be worth trying it and seeing if that fixes the issue.

 

Well I'm just getting off work so when I get home I'll check a fee more grounds and run up to auto zone and get that switch it was jacked anyway,maybe I'll have some luck

 

ok sounds good let us know what happens it that fixes the issue.

 

I did not remember that. Thanks.

So G303 is perhaps on the back panel, in the rear compartment, behind the trim?

 

No G303 will be in the passenger compartment. between the dash and the back seat.

 

Hmmm...then I wonder why they call it's location, "center of end panel"? There's no "end panel" in the middle. I wish these books had component location views for this sort of thing, but I'm not finding one.

 

Some good info in here already. Might help you.

These are the Body wiring diagrams from the 1989 Firebird manual.

My car did much of the same stuff, spent god knows how long before someone suggested a ground issue. Turns out i was missing the ground that is directly under the steering column. It caused all of my gauges to die except the gauge lights when the headlight switch was turned on, unless I opened the door. When the door was open, everything worked right.

It was ALL due to the single missing ground that had been cut so far back the wire disappeared into the loom.

 

It very well could be then with the passenger compartment all open to the trunk then

 

Also check the turn signal switch.. everything runs through it

 

so umm yea i cant figure this out all new grounds and its sill lighting everthing up any other ideas guys????????

 

Its still a ground, and the unfortunate part is tracing it out. You'll basically have to methodically check each and every ground location. Which sucks, I know, I have been there.

 

try to eliminate the circuit by making the problem happen and then start pulling fuses. When you get to a fuse that causes the problem to go away then you know where the problem lies....it will be within that circuit that the fuse controls. Try that and see what you can get out if it. Thats what i end up doing when i get to a problem like that.

 

okay im about to give up on this pos flashers have been replaced all bulbs and almost all wring so somethings still wrong any help?? thanks guys

 

It's probably not a ground.

It's a short (unintended connection) between the brake light circuit and the tail light circuit.

Most likely, a fornicated bulb socket in the rear, with the brake/TS light contact and tail light contact touching each other.

Reason the dash lights light up is, the dash lights are on the tail light circuit to begin with (so that they come on when the TLs come on, NOT the headlights); when you apply power to the brake lights, the bad socket sends power into the TL circuit as well.

The chime is connected to the TL circuit as well, NOT the headlight circuit.



It IS NOT:

• Flasher
• Anything in the steering column (tail light circuit doesn't go there... no opportunity for a short)
• Anything behind the dash (brake light circuit doesn't go there)
• Fuse

It is NOT PHYSICALLY POSSIBLE for any of these things to force brake light current through the tail light circuit.

First thing I'd suggest doing is, remove all the brake/tail bulbs. Verify that the problem goes away, by pushing the brake pedal. If it doesn't, inspect the sockets CAREFULLY, making sure the contacts aren't touching. (they frequently get damaged by the twisting action of changing a bulb when there's corrosion and whatnot causing the parts not to slide around easily like they're supposed to) Replace any that are. Might want to consider just swapping em all out ANYWAY, if they're not in pristine condition. Push the brake pedal and see if the problem is still there. Repair sockets until the problem is gone, with no bulbs installed. Replace the bulbs one at a time, testing as above after each one. Use that light bulb grease you can get at the store to keep the corrosion minimized.

If installing a bulb brings the problem back, check the voltage on the outer shell part of the bulb; should of course be near zero (ground) at all times; if it's more than a fraction of a volt, then the problem is a ground connection to that bulb. Probe the black wire behind the socket; if the bulb shell has voltage on it but the wire does not, then obviously the socket is failing to connect to the bulb, and is bad. If the wire has the same voltage as the shell, then the socket is good, but the wire itself has a bad connection to ground. Follow the black wire all the way to where it connects to the car body and repair whatever deficiencies you find.

Remember, it's just a car (simple), and just electricity (even simpler); the simplest part of a car at that. Use logic and reason and your understanding of electricity acquired in grade school science, it will lead you RIGHT STRAIGHT TO the source of the problem.

 

@Sofa - Good tip pulling tail light bulbs.

Potential sources: bad ground, shorted wire in harness, bad socket, bad bulb, bulb not inserted properly contacting both tail and brake contacts.

 

It's very common to find that someone has grunched a single filament bulb into one of the dual filament sockets. This will short the two circuits but still allow the bulb to light.

 

MoJoe hit on pretty much all of the possibilities, including some of the "far from likely" ones. Thank you Joe, you're on task here, for sure.

Short between 2 wires, for example. Yes, absolutely, it is capable of creating the symptoms you observe. But... "likely"? maybe not so much.

Study my signature - EVERY SINGLE WORD, one word at a time - for a VERY valuable troubleshooting attitude and mental discipline. Concentrate on the words "simplest", "all", "facts", "usually", "right". IN THAT ORDER.