OK, i would have had a much better summer vacation if I had known this before setting out. For me, it sucked to learn, but for you it might be helpful.


IF the ABS/TCS warning lights come on in the dash, and the TCS shuts itself off, this may very well mean you have a mechanical problem.

My truck started exhibiting weird behavior this summer where the TCS would spontaneously shut off, usually when the truck was wet (mud, etc.). I took it in several times to have the dealership look for a loose sensor wire or something that woul short when when (i thought electrical due to the water-factor, made sense). They consistently found nothing, the problem always returned. I could never get it to them when the problem was occuring because it always "fixed itself".

I set out for summer vacation a few weeks ago to Utah to do a little 'wheeling and not talk to anybody for a few days, and noticed on the bumpy hill thats optional on Fins n Things that my truck was spilling fluid. BAsically, when the truck got steep, oil flowed off the skid plate.

Soon thereafter, the TCS shut down, and eventually the front diff gave out. When i got it to another dealer, the service dude told me that the ABS system on the H2 (and apparently alot of vehicles) is programmed to shut down when mechanical problems occur. So if something goes wrong, you lose the ABS. There was a reason for this that i didn't really understand. And, he said, based on some rust around the crack in my diff, it had been cracked for a long time, but just a tiny little crack in the diff that somehow didn't blow apart.

The point being, if you have ABS/TCS shut-downs, you may have a mechanical problem and you may need to find a better mechanic if yours doesn't find anything wrong. Otherwise your vacation may wind up touring in a rental instead of a hummer.

I have heard of this behavior on at least one other H2 as well - spontaneous TCS shut-downs. However, that truck changed owners and I lost track of it, so i don't know if this was a similar situation or not.

 

my tc light has done that to me twice, both times i was stuck in the mud with wheels spinning and the little tc light with the slash through it comes on and stays on until i turn the ignition off then back on.

 

I am not alone!!!!!!!!!!!!!!! I have recently purchased a 2003 h2 and my abs, tc warning lights will not go away. I had it hooked up to the computer and was told it needed new abs pump, that it was showing code for pump failure. I had that replaced as well as abs sensor. The code was zapped at dealer and was ok for about 10 feet, then the lights came back on again. I cannot get a straight answer from anyone and I really dont feel like paying a dealer ($94hr) to diagnose a problem that he says might take all day. When you say that there could be mechanical problems, what is the most common? The computer just shows abs circuit failure and nothing else. Any ideas would be helpful? Thiis is driving me crazy..................On another issue.............about a week ago the entire instument cluster went haywire, every light came on, every code was displayed and it wouldnt stop beeping, windows didnt work, it was like the thing was posessed. I pulled over, shut it off and all was good, except for usual abs, tc warning lights. I love this truck but feel i might have got a lemon. Any suggestions would be greatly appreciated........thanks

 

Thought I would revive this. Intermittently at low temps you start the rig and the TC and ABS lights stay on. They will stay on for as long as you drive it. However, if you turn it off and re-start, they both go out. This isn't to say they may not come back on when you start it a few hours later. They have yet to come back on after the re-start. Any suggestions? I can't imagine how long it would take the dealer to "diagnose" this, if they haven't seen it before.

Thanks!

 

mine is doing exactly the same thing you described, WTF - my wife was about to deliver our kid's to daycare this AM & she comes in the house & says the H2 dash is going crazy?

 

I have a 2009 H2 LUX. It does not have the older TCS you guys have but the newer Stabilatrack system which operates in a simular mannor to a point.

When bringing my 09 home from the dealer in Pompano Fla. I had the ABS and Stabilatrack lamp go on. They are both the same ICON on the dash face....one overlapping the other.

It would go on and off thru out the whole trip home to NJ. After restarting, it would be out then I would go a few miles and it would come back on...

Finally I called onstar and got a Vehical Tech on the line and he determined that the ECM thought my left wheel was doing Fifty MPH while My right wheel was going 70 MPH. Turn sout that the Speed sensor cable on the left front wheel had popped out of it's clip and was rubbing on the upper control arm which wore thru the insulation and was causing a intermitent short.

When I got home I took it to my old HUMMER Dealer who replaced the cable and sensor. Problem solved... In my case...any difference in speed sensed by the ECM will turn off the ABS and Stabilatrack. I would also assume that tire size and inflation which would effect rotaion speed must be the same on all for wheels for the system not to shut down.

Just My $.02 Worth

 

the abs system will turn it self off if any part malfunctions with it. This is because if a sensor is out of sync it can cause the break peddle to react poorly or improper due to wrong input. We have replaced alot of front wheel abs / speed sensors and hubs due to mud and stuff like that tearing those components up. we have also have found that the wires going to the front speed sensor can break inside the harness and go on and off at times. it is hard to tell someone what is wrong due to so many components all working in sync without a scanner . it can pin point the problem 95% of the time as long as it happens during testing. but wiring problems can haunt you to death. this is not just a hummer problem , a lot of gm vehicles suffer from this . as far as one point if the light on ,the abs is off and it will act just as a normal truck without abs . but you should have a trusted shop look at it just incase it is a hub or something like that.

 

as far as the dash issue, the dash cluster , BCM or loose ground under the dash near kick panels can cause this problem. most cases if its the BCM it sets a code in the BCM itself. any modern scanner can check the BCM for codes. we have replaced more of dash clusters then anything. but you should not by no means just replace the dash with out checking it out first. I would check for lose grounds first thats easy to do they are hidden under the kick panels , once removed you can just look at any wires mounted to the metal body and check them for being lose..

 

Based on the provided information, which was very helpful, here is what I discovered. The ABS lines running from the hubs run up to connectors that are attached on the top of the frame rail. The frequency at which ABC/TC the lights come on seems to be strongly affected by whether these connectors were recently wiggled. Thus, I would expect that the source of the problem has likely been discovered - yes the problem could be a short in the wires themselves or farther "up" the line. However, believing in trying the obvious first, I'm going to pull these connectors apart, clean, and grease them. As they are basically "unsealed" and just sitting there, I rather expect that salt has gotten inside them and is doing what salt does. Not sure when I will get to this, as this isn't a top priority on my to-do list, but if it works, I will let you know.

Thanks again for the help!

 

OK, so I cleaned and greased the connectors on the frame rails. The incidence of the problem decreased significantly - but it still happens on occasion. So, you guys were right on with regard to the cause, now my issue is just what will be required to fix it. I guess the next thing to try is replacing the wires - if such can be done without opening up a harness. I haven't looked at it yet, just thinking out loud. Will continue to update as I work through this issue. Hope someone finds it helpful at some point.

Thanks!