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Home >> Chevrolet >> 2000 >> Tracker 4D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P1408: Manifold Absolute Pressure Sensor Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Start engine and let idle. Warm engine to normal operating temperature. Using DVOM, backprobe MAP sensor harness connector input circuit. If voltage reading is 0.2-4.6 volts, go to next step. If voltage reading is not 0.2-4.6 volts, go to step  4.
  3. Turn ignition on, with engine off. Using scan tool, clear DTCs. Operate vehicle within FREEZE FRAME conditions. Retrieve DTCs. If this DTC resets, go to next step. If this DTC does not reset, see DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect MAP sensor harness connector. Turn ignition on, with engine off. Using DVOM, check MAP sensor reference voltage at MAP sensor harness connector. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step  8.
  5. Using a test light connected to battery voltage, probe MAP sensor ground circuit at MAP sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  9.
  6. Check for an open or short in MAP sensor input circuit between MAP sensor and PCM. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to next step.
  7. Turn ignition off. Reconnect MAP sensor harness connector. Turn ignition on, with engine off. Using DVOM, backprobe MAP sensor input circuit at PCM harness connector. While observing DVOM, apply a small amount of vacuum to pressure passage at MAP sensor. If voltage drops, go to step  11. If voltage does not drop, go to step  10.
  8. Check for an open or short in MAP sensor reference voltage circuit between MAP sensor and PCM. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to step  11.
  9. Check for an open or poor connection in MAP sensor ground circuit between MAP sensor and PCM. Repair as necessary. After repairs, go to step  12. If circuit and connection are okay, go to step  11.
  10. Replace MAP sensor. After replacing MAP sensor, go to step  12.
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  12. After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
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