03 denali xl

[chr!s]

what causes the reduced power mode?

denali just started squeeling under the hood, sounds like it is coming from the power steering? help

[gmtech4]

reduced power msg tells you there is a diag trouble code (DTC) in the ECM,relating to the APP (throttle pedal) system,you take it to get it diag'd,,so we are no good to you there or the squealing ,as its an audio thing we cant hear it ,have the garage look at that for you to ,it could be several things ,

 

see your owners manual for more info on messages coming from the cluster

 

welcome to the site !!!

[SouthCo]

Welcome to the site. Like Rob said, could be several things causing reduced power. On my 03 Tahoe it was the the Throttle body sensor. Had to replace the whole throttle body but she is still rolling (my cousin owns it now) with just over 200k miles.

[djm3000]

This happenned to me then resolved itself.

I think I disconnected the battery and let it sit for an hour or so - to let the power drain out of the system - and then reconnected the battery.