Diagnostic System Check
CAUTION:
DO NOT replace BCM unless there are no VCM DTCs and a current BCM DTC exists after system check and DTC test has been completed. DO NOT replace BCM based on history DTCs.
NOTE:
System tests are written specifically for General Motor's Tech 2 scan tool. A generic scan tool may not be capable of performing all necessary test functions.
- Turn ignition switch to RUN position. If SECURITY indicator light turns on, go to next step. If SECURITY indicator light does not turn on, diagnose instrument cluster indicator light circuits. See appropriate ANALOG INSTRUMENT PANELS article.
- If SECURITY indicator light turned on and remained on for more than 5 seconds, go to step 5 . If SECURITY indicator light does not remain on for more than 5 seconds, go to next step.
- If SECURITY indicator light turned on for 3 seconds, turns off briefly, and then flashes on and off, go to step 5 . If SECURITY indicator light operation is not as specified, go to next step.
- If SECURITY indicator light turned on for 3 seconds, turns off for 2 seconds, and then turns on steady, go to step 1 . If SECURITY indicator light operation is not as specified, go to step 7 .
- Connect scan tool. If scan tool powers up, go to next step. If scan tool does not power up, diagnose communication problem. See appropriate BODY CONTROL MODULES article.
- Turn ignition switch to RUN position. Using scan tool, check for Passlock(tm) DTCs. If scan tool will not communicate with vehicle, diagnose communication problem. See appropriate BODY CONTROL MODULES article. If Passlock(tm) DTCs are present, see DIAGNOSTIC TROUBLE CODE INDEX table.
- Using scan tool, monitor Passlock(tm) code in Passlock(tm) data list. If scan tool does not display a value of OPEN, go to next step. If scan tool displays a value of OPEN, see DTC B2958: PASSLOCK(tm) SENSOR DATA CIRCUIT HIGH under DIAGNOSTIC TESTS.
- Attempt to start vehicle. If engine does not crank fast enough to start, diagnose starting and/or charging system. See appropriate STARTERS or GENERATORS article in
STARTING & CHARGING SYSTEMS. If starting system is okay but engine does not start, see appropriate BASIC DIAGNOSTIC PROCEDURES article in
ENGINE PERFORMANCE.NOTE: If area of fault can not be located and scan tool communication is possible with no DTCs set, diagnose by symptom. See SYMPTOM TESTS .
DIAGNOSTIC TROUBLE CODE INDEX
| DTC | Description |
|---|---|
| B2947 | Passlock(tm) Sensor Power Circuit Low |
| B2948 | Passlock(tm) Sensor Power Circuit High |
| B2957 | Passlock(tm) Sensor Data Circuit Low |
| B2958 | Passlock(tm) Sensor Data Circuit High |
| B2960 | Passlock(tm) Sensor Data Incorrect But Valid |
| B3031 | Controller In Learn Mode |
| B3033 | System Indicates Tamper |