No Communication with PCM - DTC MIL ZB

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

A tech may call stating that he cannot communicate with the PCM with or without the Candi module installed.

Inspect to see if the 12 volt reference signal to the cam sensor (ckt 631/812) or crank sensor (ckt 1867) is shorted to ground(ref.: SI document number 1218025). If it is, the PCM will not communicate with the other modules on the BUS or with the Tech 2.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

(04 Chevrolet Malibu)

.