H3 Brake light on and will not go out

Dinglezz · Sep 3, 2017

Ok , my first post so try to be gentle. 2006 Hummer H3, 3.5L 5cyl. 200km

Recent work completed, new trans cooler, new rotors and pads, new left wheel bearing, fixed fuel pump and ran new lines.
Brake light recently came on (like the park brake light) and I've checked the following. The park brake fuse, the brake level, the brake lines, all the pads and rotors. Not down any fluid and no leaks. Also have the ABS traction control light on, but have been emptying 1/4 can of electrical connector cleaner to the plug under the transfer case as per the direction here.
Braking in the hummer is unchanged. No difference in pedal feedback, and hummer stops normally. I did notice that when I have to slam on the brakes for random idiots around me, the hummer does seem to dive hard front and pull slightly front right??

I thought initially I had a seized caliper but checked all them and they still work all though could all stand to be replaced. Someone mentioned air in the brake line??

Any advice greatly appreciated.

Thanks in advance

JPaul · Sep 3, 2017

did you check the ABS sensors at the axles to make sure they're still plugged in and everything?

Happy Hummer · Sep 3, 2017

There is a thread on here that talks about this problem with brake lights staying on. It is something to do with the switches at the pedal or the wiring at the hitch between body and frame etc... Lol! I'm trying to get this from memory because thread is not saved on my tablet.

4speedfunk · Sep 4, 2017

I think he means the brake warning light on the dash (not the actual brake lights on the rear of the vehicle).

If it didn't do it before, and it does it after you worked on it...then it most likely has to do with something you worked on. Most likely an ABS sensor. That can set an ABS and/or Brake warning light.

A code scan would tell you for sure. I believe the H3 can actually tell you which corner has the problem but, you need a $5000 diagnostic machine to read it. A simple hand-held reader won't give u this info.

lowtrac · Sep 4, 2017

Go by Advance Auto Parts or Auto Zone. They can scan codes for you. Ask if they have a scanner that'll read ABS codes. 4speedfunk is most likely correct that a low end scanner won't give you in-depth diagnostic info but it's worth a shot. Better than shooting in the dark.

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Mr_Rich · Sep 4, 2017

I've got one of those HF Centech scanners and it has a provision to read the braking system codes. The problem is that the Hummer option doesn't work with it. My work-around is that if I set it for '09 GMC/ Chevy Trailblazer it will read the codes and enable me to clear them. I actually have a STAB SYS code that appears intermittently but doesn't stay as a hard code. What I mean by that is that a hard code can be erased by correcting the equipment fault that isn't intermittent. Those kind of faults are like chasing your tail...
I might add that with my old Chevy truck (OBDI) the brake light blinks to signify a code vs. the check engine light blinking to determine engine codes.

alrock · Sep 4, 2017

I had that light come on during a brake service as an ABS fault - a friend pressed the brake pedal when the caliper was not attached, overextending the pistons (but not ruining) the caliper. It took a Tech 2 to reset it and a shop did it for free.

Pulling under braking may signal a worn out control arm bushing - likely the lower control arm but possibly the upper.

Bruces · Sep 4, 2017

Every time I've removed the caliper (half shafts and hubs) after reinstall the first time you hit the brakes a code is tossed on abs. After pumping brakes up to get brakes reset and where they should be after clearing code with scan tool the codes would not return.

if it pulls your alignment is either off or brakes on one side are grabbing more than the other side.

I agree with the other post. About 6-10 months ago there was a post where the break light stayed on. The culprit was either a burnt bulb somewhere else (i think reverse), shorted wiring harness above muffler on Frame or switch on brake pedal.

Dinglezz · Sep 13, 2017

ABS sensors - Checked all these and they are good to go.

Auto parts zone? I dont think we have these in Canada, or at least not where I live in beautiful Bruce County Ontario. My mech neighbour says he has a old code reader that will read the brake light code and I can go from there?

ABS light and now Brake light - makes me think it is a major ABS component failure. I forgot to mention that for the last few months the hummer will lock up if you smash the brake pedal(not just a hard braking) to the floor in an emergency. Ive had to do it twice.

Yes, i read the post on the brake light. This is the dash warning park light. Same one that comes on if you apply your park brake. No my park brake is not stuck on. Still works good actually. Use it when Im putting the boat in and out of the water.

STill I continue to check brake fluid, hoses and connectors daily until I solve this problem WITHOUT PAYING SHOP LABOUR!

4speedfunk · Sep 14, 2017

If you've had brake issues for a couple months...and the dash light is on...then you definitely got something failing. Front hub would be my guess.

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Dinglezz · Sep 14, 2017

Three out of four wheel speed sensors are not functioning. I will endeavor to fix this but am just ELATED that its not a major brake issue. Freaking love that super duper shop computer. Tells you everything!

4speedfunk · Sep 14, 2017

Are you sure? All three listed say "YES". Maybe the issue is the one that is not listed (the front left one)? Seems weird that three would fail at the same time.

citiboy · Sep 15, 2017

Do a road test with the scanner and check the speed reading on each individual sensor.

Kick'n Dust · Sep 16, 2017

Using a scanner to observe wheel speed sensor signal while driving is step one. Then determine how many sensors are not responding. Use a wiring diagram to determine what circuit is common to the faults. If you have access to diagnostic information for the codes set you will be able to reduce your diagnostic time considerably.

Based off the codes you have you either have a wiring issue or a failed sensor(s). A failed electronic brake control module (EBCM) will set a "U" code most likely, so this is likely not your issue.

Or just pay to have a professional do it and have it fixed in a day or two

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Kick'n Dust · Sep 16, 2017

I'll try to post some pictures of GM diagnostic information before I leave work today

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Kick'n Dust · Sep 16, 2017

This is bulletin GM has. Not sure if we will be able to read it...

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Kick'n Dust · Sep 16, 2017

Oh yeah that is legible. I'll post more soon

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Kick'n Dust · Sep 20, 2017

Sorry I've been slammed and now I'm driving to Traverse City to pick my dog up from the Humane Society because she decided to run away on a camping trip 16 days ago.

Did you ever resolve the abs issue? This post has been quite for a few days

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Dinglezz · Sep 21, 2017

Did the speed test same night with the scanner hooked up. It showed three of four sensors failed.

Have not fixed it as of yet. Currently taking advantage of +30C temps in Ont and taking care of rust spots. Door sills, passenger door handle, etc.

H3 Brake light on and will not go out

Dinglezz

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JPaul

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Happy Hummer

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4speedfunk

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lowtrac

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Dinglezz

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