Entering & Exiting Diagnostics: Notes

NOTE: Diagnostic system cannot display ECM trouble codes on speedometer for VIN J engine, and will display "Err" when attempting to display ECM codes for VIN J engine. DTC display and clearing DTCs for VIN J engine is only accessible with a scan tool, such as the Tech 1.

Speedometer, odometer and trip monitor are used to display Central Control Module (CCM) information while in diagnostic mode. Speedometer displays CCM, ECM and Electronic Brake and Traction Control Module (EBTCM) Diagnostic Trouble Codes (DTCs). Odometer displays CCM data. Trip monitor displays system being tested and test being performed. See Fig 1 . Driver Information Center (DIC) buttons are used to transmit instructions to CCM while in diagnostic mode. See Fig 2 .

Fig 1: Identifying CCM Diagnostic Display

Courtesy of GENERAL MOTORS CORP.

Fig 2: Identifying Driver Information Center Buttons/Functions

Courtesy of GENERAL MOTORS CORP.

If a code-setting malfunction is present, "SYS" (SYSTEM ERROR) will flash on instrument cluster trip monitor. SYS will flash 3 times every 15 seconds when a current code is set. If a PASS-Key(R) malfunction code (DTCs 51-53) is set, SECURITY indicator will flash. If DTC 54 is set, "SYS" and SECURITY indicator will flash simultaneously.

NOTE: Ensure A/C fuse is not blown. If fuse is blown, CCM will not receive IGN 3 power and will not enter diagnostic mode. DTC 16 will be set if A/C fuse circuit is open.