i have a 2006 h3 automatic today i was pulling out onto the road and there were cars coming so i floored it and as soon as i did the engine light and traction light came on and it just lost power like almost to an idle so pulled over and it was idling very rough so i shut it off and my uncle haul it to his body shop i called onstar to run a diagnostic test and they said something about the brake system and the stability system was messed up at put it in a "low power mode" has anyone ever had this problem?

 

I have a 08 Hummer H3 have the same issues, but i replace the throttle body, spark plugs,thermostat, but still not running wright, it has been with a mechanic for a wk now, thinking of going some where else but now i have to pay this mechanic $200 dollars before i go some where else, but any help would be very helpful. thanks i was thinking maybe a electrial person but that will get expesive. thanks rosa hernandez

 

Since you are taking guesses.... and did not provide any code information

grabbing one piece of your description (floored it and as soon as I did....), you have a bad PPS. That is Pedal Position Sensor. It went when you suddenly mashed it.

Reduced Power mode comes on for several reasons not brake related. One of those happens when the PPS loses accurate communication from the TPS (Throttle Position Sensor). These trucks are fly by wire, no throttle cable. If the PCM cannot correlate the position of the accelerator pedal with the position of the throttle plate in the TB, it throws a code and goes into limp mode. Not an uncommon failure, and may or may not include rough idle. On the other end, it could also be the TPS went bad and the PPS is fine?

The PPS is built into the accelerator pedal assembly, it is a plug and play swap, easy to do, costs about $40 for 08s and down, like $60 for the 09+.



Post the code(s) if you want better than a guess.