Possible causes

– Dead or weak battery
– Poor circuit connection – Check Throttle Actuator Control (TAC) module connector for water
– Faulty Throttle Actuator Control (TAC) module

When is the code detected?

The Engine Control Module (ECM) has detected a loss of data or invalid data from the Throttle Actuator Control (TAC)

Symptoms

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

P1518 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 P1518 code