Possible causes

– Faulty Throttle Actuator Control (TAC) module
– Throttle Actuator Control (TAC) module harness is open or shorted
– Throttle Actuator Control (TAC) module circuit poor electrical connection (loose or broken wires)

Tech notes

There is a factory service bulletin for the P2108 code on following Cadillac vehicles:

2006-2007 GMC Savana 1500/2500/3500
2006-2007 GMC Sierra
2006-2007 GMC Sierra Flex Fuel
2006-2007 GMC Sierra Hybrid
2006-2007 GMC Sierra Performance Edition
2006-2007 GMC Sierra 2500/3500 HD
2006-2007 GMC Yukon

Factory Service Bulletin GMC OBDII Code P2108

When is the code detected?

The Throttle Actuator Control (TAC) module is unable to write or read data from the Random Access Memory (RAM)

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– No throttle response

P2108 GMC Description

The Throttle Actuator Control (TAC) module contains data which is essential for proper TAC operation. The TAC module continuously test the integrity of this data. When the TAC module is unable to write or read data to and from Random Access Memory (RAM), or the TAC module is unable to correctly read data from the flash memory or and internal TAC module processor fault is detected and the Detected Trouble Code (DTC) is set.

GMC Technical Service Bulletins for P2108 code