After sitting for several months my hummer would not idle properly and had an engine code P2101. The dash also indicated traction control and low power mode issues.
i cleaned the mass air flow sensor and checked the air cleaner, then checked the wires and vacuum hoses around and under the throttle body. Then pulled the throttle body and cleaned it with a small brush and the proper cleaner. Nothing helped the issue I had. Had a mechanical shop take a look at it who has more testing equipment then I've got. Turned out the low volt power wire from the fuse box to the main computer had a short to ground in the main wiring harness. It was easier and cheaper to cut the wire at the fuse box and computer and replace it with a new wire, soldering it in place and not using crimp joints, then trying to find the actual short. Hope this helps some of you who have the same problem. Runs like a champ again.

 

Welcome.

Couple observations. You did not tell us YEAR and MODEL Hummer you are talking about, so not much help so far.

Works like this.... You post vehicle tech questions/info in the vehicle section only. Example: All H3 questions go in the H3 Section. If you would provide the Year and Model I can move this for you.

 

2006 Hummer H3 67000 miles

 

Thank you, moved.

And thanks for the repair tip on the problem.

 

Can you post a picture of the location of the wire connection? Or tell us which pin it is on the ecu and the fuse panel? I have an h3 2007 with the same issue

 

Hopefully the wiring on an 06 and the 07 H3 are the same. That being said you will need to remove the fuse cover plate then the two red hot leads from the fuse block. Separate the two halves of the fuse block so you can access the wire connection plugs. you want the gray plug, or the one closest to the battery. Disengage it so you can see the wires running into it. You want the white wire with the black tracer. This wire runs to the control modular that is mounted on the passanger side of the firewall. There are three plugs running into it, you want the blue plug or the one closest to the fender. Yeah it's the hardest one to get too. After you get it off turn it upside down and look for the same wire, white with a black tracer. Mine had grounded out so it was faster and and cheeper to cut the wire and replace it with a new wire. It is hard to find a wiring diagram for Hummers online. Try to find someone who works in a shop who has access to Alldata. It is a good site for mechanics but you have to pay for the usage.
Working on the fuse block in a hummer is a real pain. You will find it easier if you remove the battery so you have more room to work. Unless you have worked with GM wiring plugs and know how to unhook and reconnect them look on you tube for a video on how to do it without breaking it.
Diagnosing the problem is always harder then doing the actual repair, especially with newer cars. If this is your problem and you are doing your own work I just saved you a grand! Good luck, and as always, keep the shinny side up.

 

Thank you very much Brinks, I will start on it tomorrow morning, I have a shop manual with the wiring for my truck so hopefully it will be easier! Will invest the 1k on goodies for my h3