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Home >> GMC >> 1998 >> Forward Control 4.3 W, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - Introduction >> Self-Diagnostic System >> On-Board Diagnostic (OBD) System Check >> 4.8L, 5.3L & 6.0L

4.8L, 5.3L & 6.0L

NOTE: Ensure battery is fully charged and check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT turn ignition off during the following procedure unless instructed to do so.
  1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to DLC DIAGNOSIS OR NO SCAN TOOL DATA .
  2. If scan tool displays PCM data, go to step  4. If scan tool does not display PCM data, go to next step.
  3. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS 2 MESSAGE MONITOR. If scan tool displays any other modules as ACTIVE, go to DLC DIAGNOSIS OR NO SCAN TOOL DATA . If scan tool does not display any other modules as ACTIVE, check scan tool connection. Check circuits between DLC and control module which does not communicate with scan tool. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
  4. Using scan tool, monitor IGNITION 1 voltage while cranking engine. If voltage is near battery voltage, go to next step. If voltage is not as specified, diagnose system using appropriate test for DTC P0562. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
  5. If engine starts and continues to run, go to step  8. If engine does not start, or starts and then stalls, go to next step.
  6. If any PCM, BCM or VTD DTCs related to vehicle theft deterrent system are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to next step.
  7. Using scan tool in BODY mode, monitor PCM/VCM FUEL CONTINUE parameter while cranking engine. If scan tool displays FUEL CONTINUE as NO, diagnose theft deterrent system. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. If scan tool does not display FUEL CONTINUE as NO, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  8. Using scan tool, capture DTC FREEZE FRAME and/or FAILURE RECORDS information. Monitor DTC information. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
  9. Compare scan tool engine data with typical control system data values. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.
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