DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681, P1683 or P2610: Description
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic applies to internal microprocessor integrity conditions within the powertrain control module (PCM) and the throttle actuator control (TAC) system. This diagnostic also addresses if the PCM is not programmed.
The PCM monitors its ability to read and write to the memory. It also monitors a timing function. The PCM and the TAC processors are used to monitor the TAC system data. Both processors monitor the other processors data to verify that the indicated accelerator pedal position (APP) calculation is correct. The PCM performs an intrusive test in order to confirm that the APP signals are not shorted together. The PCM accomplishes this by pulling the APP sensor 2 low momentarily and looking for sensor 1 to also be pulled low.