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GMC Forum: reduced power mode
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Old 11-10-2019, 12:29 AM
Sir Real Ed Sir Real Ed is offline
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Join Date: Apr 2012
Posts: 3
Default reduced power mode


2002 GMC 2500HD, 8.1 liter, Allison Transmission, 4x4.

The truck has been sitting for about 3 weeks. The day before my wife reset the clock on an after market radio that was installed a couple years ago.

The truck started fine, but immediately went in to reduced power mode and the service engine soon light came on. Shutting off the truck and re-staring it produce the same result 2 more times. On the fourth start the truck reverted to normal mode, but the service engine soon light stayed on.

Since then I have driven the truck about 50 miles with multiple starts and everything has been fine. The other day I reset the "service engine soon" light. Hooking up the scanner revealed two codes "P1515" and "P1515 pending." I cleared these codes and have not driven the truck since.

Any suggestions? Thanks in advance!
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Old 12-01-2019, 04:30 PM
98trck 98trck is offline
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Drives a '11 sierra 1500
Join Date: Feb 2011
Location: Chandler Az
Posts: 276

i googled it

'TAC (Throttle Actuator Control)'

try unplugging all wires to the throttle body and reconnect

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p1515, reduced power mode
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