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Home >> Oldsmobile >> 2003 >> Bravada AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 4.2L >> Diagnostic Tests >> DTC P0105: Map Sensor Circuit - Insufficient Activity >> Diagnostic Procedures

Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Inspect for the following conditions:
    • MAP sensor seal missing or damaged.
    • Restrictions in the MAP sensor vacuum source.
    • Vacuum hoses disconnected, damaged, or incorrectly routed.
    • Vacuum leaks between the intake manifold and the engine.
    • Vacuum leaks at the throttle body.

    Did you find and correct the condition? If yes, go to step  25. If no, go to next step.

    3. NOTE: The vehicle used for the comparison is not limited to the same type of vehicle as is being serviced. A vehicle known to provide an accurate reading is acceptable.
  3. Do you have access to another vehicle in which the MAP sensor pressure can be observed with a scan tool? If yes, go to next step. If no, go to step  5.
  4. Install scan tool. Turn ignition on, with engine off. Monitor scan tool and record the MAP sensor pressure. Compare the MAP sensor pressure to that of a known-good vehicle. Is the pressure difference between the vehicles less than 0.89 in. Hg (3 kPa)? If yes, go to next step. If no, go to step  11.
    5. NOTE: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. See SENSOR OPERATING RANGE CHARTS - TRUCKS article. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.
  5. Turn ignition on, with engine off. Observe the MAP sensor pressure with a scan tool. Refer to Altitude vs Barometric Pressure in SENSOR OPERATING RANGE CHARTS - TRUCKS article. The MAP sensor pressure should be within the range specified for your altitude. Does the MAP sensor indicate the correct barometric pressure? If yes, go to next step. If no, go to step  11.
  6. Observe the MAP sensor pressure on scan tool. Start the engine. Does the MAP sensor value change? If yes, go to next step. If no, go to step  11.
  7. Turn ignition off. Remove the MAP sensor from the vacuum source. Leave the electrical harness connected. Connect a hand-held vacuum pump to the MAP sensor. Turn ignition on, with engine off. Observe the MAP sensor pressure as you SLOWLY apply vacuum 1 in. Hg at a time. Each inch of vacuum should result in a 0.89-1.18 in. Hg (3-4 kPa) drop in the MAP sensor pressure. Increase the vacuum to 20 in. Hg (67 kPa). Does scan tool indicate that the MAP sensor pressure decreases smoothly through the test? If yes, go to next step. If no, go to step  11.
  8. Observe the MAP sensor pressure with 20 in. Hg (67 kPa) of vacuum applied to the MAP sensor. Does scan tool indicate that the MAP sensor pressure is less than 10 in. Hg (34 kPa)? If yes, go to next step. If no, go to step  11.
  9. Observe the MAP sensor pressure with the scan tool. Disconnect vacuum pump from the MAP sensor. Does the MAP sensor pressure return to the original reading observed in step  4 or  5 ? If yes, go to next step. If no, go to step  23.
  10. Inspect for incorrect cam timing, restricted exhaust flow, or worn piston rings. Did you find and correct the condition? If yes, go to step  25. If no, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.
  11. Disconnect MAP sensor electrical connector. Observe MAP sensor voltage with scan tool. Is voltage less than 0.3 volt? If yes, go to next step. If no, go to step  16.
  12. Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground with a DVOM. Is voltage more than 5.2 volts? If yes, go to step  17. If no, go to next step.
  13. Probe the 5-volt reference circuit of the MAP sensor with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  18.
  14. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the MAP sensor and the signal circuit of the MAP sensor. Does scan tool indicate that the MAP sensor voltage is more than 4.9 volts? If yes, go to next step. If no, go to step  19.
  15. Turn ignition off. Remove jumper wire. Connect a jumper wire between each of the terminals in the MAP sensor harness connector and corresponding terminal at the MAP sensor. Turn ignition on, with engine off. Measure voltage from the low reference circuit of the MAP sensor at the jumper wire terminal to a good ground with a DVOM. Is the voltage more than 0.2 volt? If yes, go to step  20. If no, go to step  21.
    16. NOTE: Disconnecting the PCM may eliminate the short during testing.
  16. Test the MAP sensor signal circuit between PCM and MAP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step  25. If no, go to step  24.
    17. NOTE: Disconnecting the PCM may eliminate the short during testing.
  17. Test all of the branches of the 5-volt reference circuit that are shared with the MAP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step  25. If no, go to step  24.
  18. Test the low reference circuit of the MAP sensor for high resistance or an open. Did you find and correct the condition? If yes, go to step  25. If no, go to step  22.
  19. Test the MAP sensor signal circuit between the PCM and MAP sensor for a short to ground, open or high resistance. Did you find and correct the condition? If yes, go to step  25. If no, go to step  22.
  20. Test the low reference circuit between the PCM and MAP sensor for an open or for high resistance. Did you find and correct the condition? If yes, go to step  25. If no, go to step  22.
  21. Test for an intermittent and for a poor connection at the MAP sensor. Did you find and correct the condition? If yes, go to step  25. If no, go to step  23.
  22. Inspect the MAP sensor for intermittent or poor connections. Did you find and correct the condition? If yes, go to step  25. If no, go to next step.
  23. Replace MAP sensor. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After repairs, go to step  26.
  24. Replace PCM. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  25. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  26. Observe the stored information, Capture Info with scan tool. Does 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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