My H2 03 is driving me crazy going into reduced power for the last 6 months. I have to pull over turn it off wait a minute or two and restart it and it's okay for a little bit I do seem to notice a fluctuation in the throttle speed at low acceleration and RPMs that's usually what sets It Off
Already replaced the electrical switch at the throttle pedal, the electrical controller unit up on the firewall driver side and an entire new throttle body, as as the code it , it was throwing, which escapes me at the moment, mentions a problem with electrical current between the three.. I guess it needs to go on a machine deep scan tool that find the problem easily? Any ideas out there?

The wires between the TAC module and the throttle body are know to break about 6" from the connector on the throttle body and will cause all kinds of issues with the drive by wire system.

They will break inside the wire coating and are very hard to find, the plug and about 12" of wire (pigtail) are sold at most local auto parts houses its so common.

Neal

If you can get it to crank without the issue then start wiggling the wires at the throttle body it will usually start acting up.

Neal

Thanks Neal for the tip, I had no idea the wires could break inside the rubber insulation, I'll check it out.

well I did replace that wiring harness I thought for sure I found the problem one of those Factory butt connectors practically fell right off but doing a quality job installing the new harness it still does not solve the problem I even did a crankshaft position sensor and still I go into reduced power mode usually when it's cold in the morning pullinh out of my driveway the RPMs fluctuate a little bit and I go into reduced power mode. I did take it to the dealer and they deep scan it and checked everything and everything seems to be working fine isn't that just amazing..

when it comes to reduced power issues the code it throws is critical to knowing where to start looking along with the freeze frame data. There are three main components to the system, peddle, throttle body and TAC module and the code will tell which one is causing the issue usually.

I've fixed a good number of them by cleaning the throttle body, most of these go into reduce engine power at low speed or during crank up and the code indicates issues with the throttle body position sensors that show a position disagree.

When cleaning the throttle body along with the carbon buildup inside the body its usually the brg's on each end of the shaft that has carbon build up inside so make sure to spray the cleaner there and then a small amount of lubricant.

Neal

i have the same issue with my hummer h2 03, i have changed throttle body 4 times from dealer (under warranty) and a new pigtail and a new padel sensor assembly twice. I still have engine reduced power and check engine on yesterday. 2 months ago rewired pigtail checked every wire to make sure if nothing is loose. It stop acting up for 2 month and drove about 2500 miles and yesterday again same issue popped right back. I have changed everything but do not know what it is. Once code is cleard drives perfect no problems at all sometimes it throws code 2 times a day with 110 miles or so. If any one have any solution it will be highly appreciated. Its been giving me code p2135 throttle/padel position sensor switch a/b voltage correlation!!!

Search on here for info on checking grounds....

It would be very helpful if you can get someone to pull the freeze frame data to see when the issue is taking place and the parameters of the critical sensors at that time.
I also would follow MixMan's suggestion and check all grounds associated with that harness, the one on the back of the drivers side head would be a good place to start (on most 6.0's that's where they stick a ground).

Neal

cannoncollector did you ever get your fixed?

You think it is ecu issue ? Thats the only thing i have not changed since this issue! Everything else is been replaced related to throttle body