Selecting The System

After trouble codes have been displayed, the Service Mode can be used to perform several tests on different systems one at a time. Upon completion of trouble code(s) display, a specific system may be selected for testing. See Fig 1 .

Fig 1: Operating Service Mode Chart

Courtesy of GENERAL MOTORS CORP.

Following the display of trouble codes, the first available system will be displayed (i.e. PCM?). While selecting a system to test, any of the following actions may be taken to control the display:

1. Depressing OFF button on the ECC will stop the system selection process and return the display to the beginning of the trouble code sequence.
2. Depressing LO button on the ECC will display the next available system selection. This allows the display to be stepped through all system choices. This list of systems can be repeated following the end of the system list.
3. Depressing the HI button on the ECC will select the displayed system for testing.
4. Depressing RESET/RECALL button on the DIC will halt diagnostics and return to normal display and operation.