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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: DO NOT perform this test if no driveability condition exists. Search for applicable bulletins before proceeding with the diagnosis. DO NOT turn OFF ignition when performing this diagnostic test procedure. DO NOT clear the DTCs unless the diagnostic instructs you to do so. If there is a condition with the starter system, diagnose starter system. See appropriate STARTERS article in ELECTRICAL. Ensure battery is fully charged and cables are clean and tight. Ensure PCM grounds are clean, tight, and in proper location.
  1. Install scan tool. Does scan tool turn ON? If yes, go to next step. If no, perform SCAN TOOL DOES NOT POWER UP in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
    2. NOTE: If using a Tech 2® scan tool, obtain the information using the Class 2 Message Monitor feature.
  2. Turn ignition on, with engine off. Using scan tool, attempt to establish communication with the Electronic Brake Control Module (EBCM), Powertrain Control Module (PCM) and Vehicle Theft Deterrent (VTD) module. Does scan tool communicate with all the control modules? If yes, go to next step. If no, perform SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  3. Attempt to start engine. Does engine start and idle? If yes, go to next step. If no, go to NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 4.0L AURORA article.
  4. Using scan tool, select the DTC display function for the EBCM, PCM and VTD. Does scan tool display any DTCs? If yes, go to next step. If no, go to step  9.
  5. With scan tool, select Captured Info in order to store the powertrain DTC information. When complete, go to next step.
  6. Does scan tool display DTCs which begin with a "U"? If yes, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If no, go to next step.
  7. Were any of PCM DTCs P0601 or P0602 set? If yes, go to DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681 & P1683: PCM MEMORY . If no, go to next step.
  8. Does scan tool display DTC P0560, P0562, P0563, P0621 or P0622? If yes, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If no, go to next step.
  9. Is customer's concern with the automatic transmission? If yes, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. If no, go to next step.
  10. Is customer's concern with the Inspection/Maintenance (I/M) testing? If yes, go to INSPECTION/MAINTENANCE SYSTEM CHECK  under DRIVE CYCLES. If no, go to next step.
  11. Check for any of the following symptoms. Hard start, surges/chuggles, lack of power, sluggishness, or sponginess. Check for cause of detonation/spark knock, hesitation, sag, stumble, cuts out/misses, poor fuel economy, rough, unstable, or incorrect idle and stalling. Check for cause of dieseling/run-on, backfire, MIL inoperative, or MIL always on. Repair as necessary. If no problem is found, problem is intermittent.
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