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Engine Controls Diagnostic System Check

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Check for applicable technical service bulletins before proceeding. Do not perform procedure if no driveability conditions exists, unless directed here from another procedure. Do not turn ignition off during procedure or clear DTCs unless instructed to do so.
  1. If a condition exists with starting system, perform engine electrical diagnostic system check. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK . Ensure battery is fully charged and cables are clean and tight. Ensure Powertrain Control Module (PCM) grounds are clean, tight, and in proper location. PCM is located in engine compartment, inside air filter housing. Connect scan tool to Data Link Connector (DLC). DLC is located below driver side of instrument panel, near steering column. If scan tool powers up, go to next step. If scan tool does not power up, perform TEST A: SCAN TOOL DOES NOT POWER UP  under SYSTEM TESTS.
  2. Turn ignition switch to RUN position. Using scan tool, attempt to establish communication with PCM. If scan tool communicates with PCM, go to next step. If scan tool does not communicate with PCM, perform TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
  3. Attempt to start engine. If engine starts and idles, go to next step. If engine does not start, diagnose engine cranks, but does not start. See NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
  4. Using scan tool, select DISPLAY DTC function for PCM. If scan tool displays any DTCs, go to next step. If scan tool does not display any DTCs, go to step  8.
  5. Using scan tool, save or capture PCM DTC information, then go to next step.
  6. If scan tool does not display any DTCs that begin with "U", go to next step. If scan tool displays any DTCs that begin with "U", perform TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
  7. Perform appropriate test for DTCs displayed on scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  8. If customer concern is not with automatic transmission, go to next step. If customer concern is with automatic transmission, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
  9. If customer concern is not with inspection/maintenance, go to next step. If customer concern is with inspection/maintenance, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  10. If customer concern is a driveability problem, diagnose by symptom. See TROUBLE SHOOTING - NO CODES - CARS article in ENGINE PERFORMANCE.
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