Entering Diagnostic Mode - Automatic Code Display Sequence

Enter Diagnostic Mode:
To enter diagnostic mode, ground pin "G" of the ALDL connector and turn the ignition switch "ON".

^ If the A/C fuse is blown, the CCM will not receive IGN 3 power and will not enter diagnostic mode. This condition should also set fault code 16.

The CCM will display any fault codes and the module for which they apply in an automatic code display sequence. The CCM is Module 1, the ECM is module 4 and ABS/ASR EBCM is module 9. During automatic display sequence, each code is displayed for three seconds, followed by a one second pause between the code display sequence for each module. The end of the code list for each module is indicated by "---" being displayed in the speedometer. If there is a communications problem between the ECM or EBCM and the CCM, the speedometer will display "ERR" when the CCM is trying to communicate with the ECM or EBCM.

CCM Diagnostic Display (Automatic Mode Display):

Specific Module Interrogation:
The particular module being interrogated is indicated on the trip monitor, and the codes are displayed on the speedometer. The speedometer also indicates if the fault code is current code or history code with a "C" or "H", respectively. All ECM and EBCM codes will be displayed by the CCM as history codes, whether they are current or history.

When all fault codes have been displayed for all modules, the trip monitor will display 1.0 and the speedometer will be blank. This indicates Manual Mode and the CCM is awaiting technician instructions.