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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. 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. Observe the DTC Information with a scan tool. Is DTC P1120 or P1220 also set? If yes, go to DTC P1120: THROTTLE POSITION SENSOR NO. 1 CIRCUIT or DTC P1220: THROTTLE POSITION SENSOR NO. 2 CIRCUIT  . If no, go to next step.
  3. Turn ignition off. Disconnect the throttle body harness connector. Disconnect the ECM harness connector. Using a DVOM, measure the resistance of each TP sensor low reference circuit, signal circuit and 5-volt reference circuit. Is the resistance greater than 5 ohms on any of the circuits? If yes, go to step  7. If no, go to next step.
  4. Test signal circuit of the TP sensor No. 1 for a short to the signal circuit of the TP sensor No. 2. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  5. Test for an intermittent and for a poor connection at the throttle body harness connector. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  6. Test for an intermittent and for a poor connection at the ECM harness connector. Did you find and correct the condition? If yes, go to step  9. If no, go to step  8.
  7. Repair the high resistance in the circuit that measured greater than the specified value. After repairs, go to step  9.
  8. Turn ignition off. Replace ECM. Perform ECM relearn procedure. See ELECTRONIC CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  9. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within the conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate vehicle within the conditions observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  10. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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