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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 367 (Engine Controls Self-Diagnostics - 3.1L Engine) >> Diagnostic Tests >> DTC P1374: CKP High To Low Resolution Frequency Correlation >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Attempt to start the engine. Does the engine start and run? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Does the DTC fail this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Turn ignition switch to OFF position. Disconnect Control Module (ICM) harness connector. Remove the injector fuse. Turn ignition switch to RUN position, engine OFF. Momentarily probe the low resolution engine speed signal circuit at the ignition module harness connector using a test light connected to battery voltage. Observe the ENGINE SPEED parameter using a scan tool. Is an Engine Speed displayed? If yes, go to step  8. If no, go to step  6.
  5. Did the test light illuminate? If yes, go to step  8. If no, go to next step.
  6. Turn ignition switch to OFF position. Disconnect the Powertrain Control Module (PCM) harness connectors. Turn ignition switch to RUN position, engine OFF. Test the ICM low resolution engine speed signal circuit for an open, a short to voltage or high resistance. Did you find and correct the condition? If yes, go to step 12. If no, go to step  9.
  7. Turn ignition switch to OFF position. Disconnect the PCM harness connectors. Test the low resolution engine speed signal circuit of the ICM for a short to ground or for high resistance. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  8. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  9. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  10. Replace the ICM. After repair, go to step  12.
  11. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  12. Using scan tool, clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate vehicle within Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  13. Using the scan tool, observe the stored information in CAPTURE INFO. Does scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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