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Home >> Cadillac >> 2003 >> Seville STS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0106: Map System Performance >> Diagnostic Procedures
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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:
    • Vacuum hoses disconnected, damaged, or incorrectly routed. See appropriate VACUUM DIAGRAMS article.
    • Manifold Absolute Pressure (MAP) sensor seal missing or damaged.
    • Restrictions in the MAP sensor vacuum source.
    • Intake manifold vacuum leaks.

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

  3. Turn ignition on, with engine off. Observe the TP SENSOR parameter with the scan tool. Depress the accelerator pedal slowly until the throttle is in the wide open position. Release the accelerator pedal slowly until the throttle is returned to the closed position. Repeat this procedure several times. Does the TP SENSOR parameter increase steadily when the pedal is depressed to more than 98 percent, and then decrease steadily when the pedal is released, returning to less than 1 percent? If yes, go to next step. If no, see DTC P0121: TP SENSOR PERFORMANCE .
    4. 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.
  4. 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  6.
  5. Turn ignition on, with engine off. Observe the MAP sensor pressure with a scan tool. Observe the MAP sensor pressure in the known good vehicle with a scan tool. Compare the values. Is the difference between the values less than 3 kPa? If yes, go to step  7. If no, go to step  12.
    6. NOTE: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. 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.
  6. Turn ignition off, with the engine off. Observe the MAP sensor pressure with a scan tool. The MAP sensor pressure should be within the range specified for your altitude. See Figure. Does the MAP sensor indicate the correct barometric pressure? If yes, go to next step. If no, go to step  12.
  7. Observe the MAP sensor pressure with a scan tool. Start the engine. Does the MAP sensor pressure change? If yes, go to next step. If no, go to step  12.
  8. Turn ignition off. Remove the MAP sensor from the intake manifold and leave the MAP sensor connected to the electrical harness. Connect a hand vacuum pump to the MAP sensor port. Turn ignition on, with engine off. Observe the MAP sensor pressure with the scan tool. Apply vacuum to the MAP sensor with the hand vacuum pump in 1 in. Hg increments until 15 in. Hg is reached. Each 1 in. Hg should decrease MAP sensor pressure by 3-4 kPa. Is the decrease in MAP sensor pressure consistent? If yes, go to next step. If no, go to step  12.
  9. Observe the MAP sensor pressure with the scan tool. Apply vacuum with the hand vacuum pump until 20 in. Hg is reached. Is the MAP sensor pressure less than 34 kPa? If yes, go to next step. If no, go to step  12.
  10. Observe the MAP sensor pressure with the scan tool. Disconnect the hand vacuum pump from the MAP sensor. Does the MAP sensor pressure return to the original reading observed in step  5 or  6 ? If yes, go to next step. If no, go to step  24.
  11. Inspect for the following engine conditions:
    • Incorrect camshaft timing.
    • Restricted exhaust flow.
    • Worn piston rings.

    Did you find and correct the condition? If yes, go to step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.

  12. Turn ignition off. Disconnect the MAP sensor electrical connector. Observe the MAP sensor voltage with the scan tool. Is the voltage less than 0.5 volts? If yes, go to next step. If no, go to step  17.
  13. Measure the voltage between the MAP sensor 5-volt reference circuit and a good ground. Is the voltage more than 5.2 volts? If yes, go to step  18. If no, go to next step.
  14. Probe the 5-volt reference circuit of the MAP sensor with a test light that is connected to a good ground. Is the test light OFF? If yes, go to step  19. If no, go to next step.
  15. 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. Observe the MAP sensor voltage with the scan tool. Is the voltage more than 4.8 volts? If yes, go to next step. If no, go to step  20.
  16. Turn ignition off. Remove the jumper wire. Connect a jumper wire between each of the terminals in the MAP sensor harness connector and the corresponding terminal at the MAP sensor. Turn ignition on, with engine off. Measure the voltage between the low reference circuit of the MAP sensor at the jumper wire terminal to a good ground. Is the voltage more than 0.2 volts? If yes, go to step  21. If no, go to step  22.
    17. NOTE: Disconnecting the PCM may eliminate the short during testing. The MAP sensor may have been damaged if the circuit was shorted to a voltage source.
  17. Test the MAP sensor signal circuit between the PCM and the MAP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step  26. If no, go to step  25.
    18. NOTE: Disconnecting the PCM may eliminate the short during testing. The MAP sensor may have been damaged if the circuit was shorted to a voltage source.
  18. 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  26. If no, go to step  25.
  19. Test the 5-volt reference circuit between the PCM and the MAP sensor for an open or high resistance. Did you find and correct the condition? If yes, go to step  26. If no, go to step  23.
  20. Test the MAP sensor signal circuit between the PCM and the MAP sensor for a short to ground, an open or high resistance. Did you find and correct the condition? If yes, go to step  26. If no, go to step  23.
  21. Test the low reference circuit between the PCM and the MAP sensor for an open or high resistance. Did you find and correct the condition? If yes, go to step  26. If no, go to step  23.
  22. Test for an intermittent and/or poor connections at the MAP sensor. Did you find and correct the condition? If yes, go to step  26. If no, go to step  24.
  23. Test for an intermittent and/or poor connections at the PCM. Did you find and correct the condition? If yes, go to step  26. If no, go to step  25.
  24. Replace MAP sensor. See MASS AIRFLOW/INTAKE AIR TEMPERATURE SENSOR under SENSORS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to step  26.
  25. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to next step.
  26. Clear the DTCs with a scan tool. Turn off the ignition for 30 seconds. Start the engine and operate vehicle within the Conditions For Running DTC. You may also operate vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to step  2. If no, go to next step.
  27. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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