Already did a search but none addressed what is happening to my '88 IROC.

I step on the brake (headlight switch in off position, fog lights in "on" position) with or without engine running and the fog, corner, front signal, dash, and tail lights go on. None flash or flicker.

However, if I have the engine running and all lights on (headlight switch pulled in "On" position), only the tailights flicker. The third brake light does not go on unless brake is depressed. Tail lights stop flickering when brake is depressed.

I haven't had a chance to look under the dash and check if wires are loose. What could it be? Thank you.

 

A bad ground in the taillight harness, or a shorted brake light bulb.

 

I checked the tailight bulbs and they were fine. Replaced both reverse lights since one was out. I didn't check the wiring harness ground since I don't know where it is. Inside the driver's quarterpanel?

I decided to disconnect the brake light switch to see what would happen. Obviously the tail lights would not go on when brake pedal was depressed. The fog lights, dash, and parking lights would not go on either. But, when the headlights (all lights on) were turned on, the tail lights would go on and still flicker.

 

Anyone have any advice? Please.

 

when this happened to me, it was a bed BRIGHT element on one of my brakes lights. bulbs are cheap, replace them 1 at a time, and you will likely find the bad one.

if that doesn't work, you are stuck looking for a short causing something to ground.

 

Changed this and still the same problem. A friend of mine said this is what caused a similar problem on another GM product.

I'll change the tail light bulbs, fog light switch, and brake light switch.

 

My friend had that problem on his Firebird when he tried re-wiring the lights for the trans am tail lights.
did you do any re-wiring or did this problem just start by itself?

I fixed my friends problem by changing the rear tail light harness back with a stock one since I didn't want to try and undo his hacked up harness.

 

Has your car been underwater for any lenth of time? CAuse that can cause some weird stuff to happen.

 

No rewiring was done to this IROC. It's really stock and the only mod is a Flowmaster #17151 3" system with single 3" tailpipe.

It did rain heavily to the point of flooding here in Hawaii right after New Year's. The car didn't sit in any deep puddles or stay in the rain while parked. I did have to drive it in the bad weather.

Four days later, I noticed the fog lights going on when stepping on the brake while driving. It doesn't do this anymore but it does when the car is not running and while stepping on the brake. Sometimes it doesn't do it at all.

I did think of rain as a possibility, but will look into the brake light switch and fog light switch.

 

Somewhere you are shorting out into the parking lights circuit. The brake light signal is jumping and lighting up the parking lights. First you need to find where the short is. Most likely it is in the rear taillight harness. Disconnect the tallight harness and see if pressing the brake still lights up the fogs/front corners. If so, the problem is under the dash, If not, problem in with the taillight harness. The taillight harness connector is on the drivers side of the trunk, behind the lockable storage compartment, or right around that area. The ground for the taillight harness is a 7mm screw on the inside back wall of the trunk, a few inches to the drivers side from hatch latch, so also make sure that is connected securely. Ans lastly, make sure the rubber grommet is in place where the taillight harness goes through the body to the bumper. If the problem only happens with the harness connected, replace it, its easier then rewiring it in most cases. I hope i was of some help, good luck... If you need pics to see where anythign is, just ask

 

I replaced the brake light switch and the problem remains.

I will start looking at the rear part of the car since what I have been doing hasn't solved the problem.

Since this part was not the problem, I took the harness that connects to the forward part (to firewall) off and noticed three wires

Light blue
Orange (hot)
Yellow (to third brake light)

With a jumper wire, I jumped the orange and yellow. No fog, parking, dash, or audible signal indicating "lights on" when engine not running.

I then jumped the light blue and orange wires. Audible noise indicating "lights on" with engine not running, fog, parking, dash light on. Simulating that the brake pedal is being depressed.

I was looking and studying the wiring schematic for this car. How much different is a 1989 camaro vs a 1988? The '88 diagram I have in the Chilton's manual is terrible vs. the 1989 diagram in the same book. Is there a source where I can buy a GM service manual?

If the rear brake light harness is bad, where is the best source to buy this?

 

What you need to do is. The connector that goes into the firewall it has moisture or somthing inside it that is making it when you put on the brakes it turn your other lights on to like it is on the same circuit. check that out and make sure it is cleaned out. that is your problem. see if that helps. It should fix the problem

 

The right reat tail lightbulb was bad. Replaced it with a new one and the problem is gone. Thank you.

 

[azzhole mode]Looks like you had the answer, like, 3 months ago.[/azzhole mode]
Glad to help