I just recently battled an issue with my 2003 Hummer H2 and thought I would share the outcome. To start things off, I was getting the tc, abs, and parking brake lights on the dash intermittently. I assumed it was a wheel speed sensor causing the issue. Wrong!! After replacing both front wheel speed sensors I was still getting the trouble alarms. I was messing around killing time at work one day and decided to lock in my differential with the 4high and 4low pushbuttons since I hadn't used it in a while. The lights just blinked and then went back to the 4H setting. At this point I was thinking that my baby was falling apart on me!!😭 little did I know that the problems are actually related! I had a friend with a snap on scan tool try and pull codes on my abs control module and my transfer case control module. He was unable to establish any communication with both modules. I was almost tempted to take it to a "stealer" and see what they would come up with. After hours of research online, I noticed that the communication problem with the Bosch 5.3 abs control module is actually pretty common. At this point, I was certain I have isolated the problem. I priced a used one through salvage yards at around $4-500!! Of course they wouldn't just sell the module alone... This actually came with the pump as well. I then came across a website CHEAP Bosch 5.3 ABS REPAIR VW Passat Audi A4 A6 A8 S4. I contacted them and stated my issue. He said he could bench test and if repairable it would only be $110. I removed my module from the pump (6 T21 torx) and unplugged the two connectors ( 30 min tops) and boxed it up. The next day it was on its way to VA. A few days later I recieved an email from them saying he had already recieved it, fixed it, and sent it back out to me. Now that is service!! Keep in mind at this point my 4 high 4 low will not change. Tonight I reinstalled my repaired abs module and started the engine. All of my lights are now clear on the dash. While it was running, I decided to try and see if my pushbutton 4 high/low would work. Sure enough they do! It appears that the abs control module and the transfer case control module are on the same datalink. I never would have believed in a million years these two issues were related! Hopefully this little write up will save a fellow H2 owner some time, trouble, and of course cash.

 

Great post. Thanks for taking the time to write it.

 

Thanks for the info, could you perhaps lead me and others to where the module is and any removal tips so we can easily get it out, ship it in and see if this corrects my issues? thanks. Also what is name of company that fixes these?

 

I would be glad to help. The module is located on the underneath side of the h2, midways on the drivers side. It is connected to a hydraulic manifold and has to be removed from the manifold itself. Very easy to do. I shipped mine into cheap-abs.com for repairs. Good luck to you