1999 Saturn SL2 Automatic, MP6FACTORY OEM SERVICE PROCEDURE

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect ECM harness connector. Using a test light connected to battery voltage, probe APP sensor ground circuit at ECM harness connector. If test light illuminates, go to step  6. If test light does not illuminate, go to next step.
  3. Connect test light to ground. Probe test light to APP signal circuit and 5-volt reference circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step  7.
  4. Disconnect APP sensor harness connector. Check resistance of ground circuit, signal circuit and 5-volt reference circuit. If resistance is infinite, go to step  7. If resistance is not infinite, go to next step.
  5. Replace APP sensor. After replacing sensor, go to step  8.
  6. Repair short to ground in circuit that caused test light to illuminate. After repairs, go to step  8.
  7. Repair open in circuit. After repairs, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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