1998 Chevy Tahoe Brake lights dont stay on

Tiny
KANE2021
  • MEMBER
  • 1998 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 77,000 MILES
I have been to a few shops. And read countless forums. I decided to post here hoping for help.

98 Tahoe if I tap the brake pedal I get brake lights. Anything harder past the first 2 inches of travel The brake lights go off. (Includes 3rd light) All other lights work.

I just took a long trip with a full interior load. 800 miles moving. Never noticed a issue until it was brought to my attention by my brother. I used a lot of cruise control on the trip.

I replaced the brake light switch on the pedal twice in fact. First time was a cheap replacement. Few days later I went to GM and got a oem switch and new clip. Still nothing.

I removed the trailer conector to see if that was it. No go. I had a alarm installed and went back to have them double check it. They said the wires are good and that because it does no have remote start the brake was not needed for the install.

Had a cd player put in. No antena was installed because they didnt have a adapter and I dont need the radio.

Brakes where replaced up front. Pads, rotors and calipers. Fluid id good. Pedal is a little soft but dealer says that should not bother it.

All fuses and bulbs are good.

During the trip I used a lot of cruise control. And tapped the brake pedal to turn it off.

One shop suggested I change the power booster because there is some play in the rod that the brake switch sits on. Well I checked it today. There is some play but the switch was not installed snug. I replaced it with the OEM switch and new clip and its snug now. Still no go.

I have played with the hazard switch, blinkers, turn, with the brake down. Nothing. Cruise works and stops fine.

I dont want to mickey mouse it because its a nice truck. Just a tap and the lights go on. Press down and they go off. I could be wrong but It feels like I have to press a little harder to get the cruise to go off. Its almost like its backwards. Tap should give me no lights but stop cruise.

Im out of ideas and running out of money to pay guys to perform work with no results. After such a long move its frustratiing. I am going to need to go through state inspection in my new state and I will not pass with no stop lights. Everything on the truck is fine except this. I love where im living now. I wish I could go cruise and check things out. I need my truck. Love this tahoe.

Sorry for the long post but I wanted to give as much detail as I could. Please if anyone has any ideas please let me know. Thank you for reading.

EDIT: More info

If I leave my foot on the brake steady during that first 1-3 inches of brake travel the brake lights stay on. Only when presses down further they go off. There is also amps installed.
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Wednesday, November 11th, 2009 AT 4:26 PM

2 Replies

Tiny
PEAR69
  • MEMBER
Everything you indicated points to the turn signal / hazard switch unit. Your brake light circuit goes through this switch after you apply the brakes. The fact that you mentioned the cruise control kinda confirms it --- Change the entire turn signal switch unit. Hope it's not too late.
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Tuesday, December 22nd, 2009 AT 4:23 AM
Tiny
KANE2021
  • MEMBER
It has been awhile. When I unclip the brake switch from the power booster rod, and leave the switch vertical it works.

The brake booster rod is loose and has a lot of play. (Also making noise) When I get under there and look, apply the brake, I see the switch makes contact, (lights on) then just slightly loses contact (lights off).

Both jobs are a pain and expensive. But im actually leaning more towards a busted diaphragm in the brake booster. Causing to much play on the rod, and not maintaining good contact on the brake switch.

My brake lights work so long as there is good contact under there. And the 3rd light has the same behavior as the side lights. (On and then off) That is what has had me so stumped. The 3rd light is doing the same.

There is air sounds and creaking when I press the brake. A lot of play in the rod (the brake switch sits on the rod). Brake pedal is loose on initial contact then a little to hard. It seems crazy, but im thinking its the brake booster. Maybe the diaphragm is busted, causing the rod to move to freely, and not making good contact on the brake switch.

So long as I have good contact I have brake lights. I can see the button on the switch. Upper right corner (just so happens to be the weakest pressure point on the setup) The button goes in, as the brake pedal is pushed down a little harder, the button moves just slightly back out.

I also have a new but now broken after market switch here. The metal switch paddle broke out of the plastic, on the lower left corner. The opposite side of the actual button. As if all of the contact pressure is being moved there.

I think the play in the rod is moving up and out on pedal pressure. Away for the button on the switch. I have spent so many hours diagnosing electrical on this. But electric is working so long and the button is pressed. It visually looks like a mechanical problem. And the brake booster is the only variable in the setup that is displaying any kind of issue.

The only problem I have with this diagnosis is I have never heard of this happening before. Lol
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Tuesday, December 22nd, 2009 AT 12:42 PM

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