Diagnostic Aids

WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: In order for the scan tool to communicate with the modules on the GMLAN data link, a CANdi module is needed between the data link connector (DLC) and the scan tool. The CANdi module is the interface between the scan tool and GMLAN communications.

The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.
If the battery positive voltage, ground circuits and connections of the DLC are functioning properly. The malfunction must be due to the scan tool/CANdi module.
Use the DMM MIN/MAX function to capture/locate intermittent conditions.