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Home >> Ford >> 1996 >> Aerostar Van Window >> Repair and Diagnosis >> External Pages >> Different car >> Section 199 (Engine Controls - Tests W/Codes - 7.3L Diesel - EEC-IV) >> Pinpoint Tests >> Pinpoint Test D: Manifold Absolute Pressure Sensor >> Diagnostic Aids

Diagnostic Aids

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  1. 1) DTC 0236

    DTC 0236 indicates faulty turbo boost sensor circuit performance. Possible causes for this DTC are:
    • Damaged MAP sensor hose.
    • Faulty MAP sensor.
    • Low turbo boost.
    • Intake manifold or crossover leaks.

    Inspect MAP sensor hose for damage, misrouting or restriction. Replace hose as necessary. Clear DTCs, and repeat QUICK TEST . If hose is okay, go to next step.

  2. 2) MAP Sensor Frequency Check

    Disconnect MAP sensor connector. Connect MAP sensor tester between MAP sensor and MAP sensor wiring harness connector. Connect DVOM to MAP sensor. Set DVOM to frequency scale. Turn ignition on. If frequency is 90-115 Hz, leave MAP sensor tester connected and go to next step. If frequency is not 90-115 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST .

  3. 3) MAP Sensor Pressure Check

    Disconnect MAP sensor vacuum hose. Using Pressure Adapter (014-00761), apply 10 psi to MAP sensor. If frequency is 135-155 Hz, go to next step. If frequency is not 135-155 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST .

  4. 4) MAP Sensor Performance Test

    Reconnect vacuum hose to MAP sensor. Disconnect MAP sensor vacuum hose from intake manifold. Install a pressure (boost) gauge to intake manifold. Road test vehicle and accelerate vehicle to achieve full boost. If boost is 12 psi or more, replace PCM. Clear DTCs, and repeat QUICK TEST . If boost is less than 12 psi, inspect intake manifolds and crossover tubes for leaks. Check turbo condition. Repair as necessary.
    5. NOTE: DTC 0237 (1996 models) indicates low input to turbo boost sensor. DTC 0235 (1995 models) indicates MAP sensor signal is inactive. If DTC 0237 is set and vehicle is a 1995 model, go to step  27).

  5. 5) KOEO DTC 0237 Or 0235
    Possible causes for these faults are:
    • Faulty MAP sensor.
    • Open or shorted wiring harness circuits.
    • Faulty PCM.

    Turn ignition off. Disconnect MAP sensor connector. Connect MAP sensor tester between MAP sensor and MAP sensor wiring harness connector. Connect banana plugs of tester into DVOM. Turn ignition on and observe tester. If Green light is on, VREF and SIG RTN circuits are okay. Go to next step. If voltage reading is less than 4 volts and Red light is on or no light is on, go to step  11). If voltage reading is more than 6 volts and Red light on, go to step  14).

  6. 6) Check For Short To Ground In MAP Sensor Signal Circuit

    Disconnect PCM 104-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Disconnect MAP sensor connector. Measure resistance between test pin No. 34 and test pins No. 25, 51, 76, 77, 91 and 103 at breakout box. If all readings are more than 10 k/ohms, go to next step. If any reading is 10 k/ohms or less, locate and repair short to ground in MAP sensor signal circuit. Clear DTCs, and repeat QUICK TEST .

  7. 7) Check For Short To Power In MAP Sensor Signal Circuit

    Turn ignition on. Measure resistance between test pin No. 34 and test pins No. 55, 71 and 97 at breakout box. If all readings are more than 10 k/ohms, go to next step. If any reading is 10 k/ohms or less, locate and repair short to power in MAP sensor signal circuit. Clear DTCs, and repeat QUICK TEST .

  8. 8) Check For Shorted VREF-To-MAP Sensor Signal Circuit

    Turn ignition off. Measure resistance between test pins No. 34 and 90 at breakout box. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, VREF is shorted to MAP sensor signal circuit. Repair as necessary. Clear DTCs, and repeat QUICK TEST .

  9. 9) Check MAP Sensor Signal Circuit Continuity

    Measure resistance between test pin No. 34 at breakout box and Light Green/Black wire at MAP sensor wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, locate and repair open circuit in Light Green/Black wire. Clear DTCs, and repeat QUICK TEST .

  10. 10) Check PCM

    Connect PCM to breakout box. Turn ignition on. Measure voltage between ground and Light Green/Black wire at MAP sensor wiring harness connector. If voltage is 4.5-5.5 volts, replace MAP sensor. Clear DTCs, and repeat QUICK TEST . If voltage is not 4.5-5.5 volts, replace PCM. Clear DTCs, and repeat QUICK TEST .

  11. 11) Check VREF Circuit Voltage

    Disconnect MAP sensor tester from MAP sensor, leaving tester connected to MAP sensor vehicle wiring harness connector. Turn ignition on and observe tester. If Green light is on, replace MAP sensor. Clear DTCs, and repeat QUICK TEST . If Red light is on or no light is on, go to next step.

  12. 12) Check VREF Circuit Continuity

    Turn ignition off. Disconnect PCM 104-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Disconnect MAP sensor connector. Measure resistance between Brown/White wire at MAP sensor wiring harness connector and test pin No. 90 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, locate and repair open circuit in Brown/White wire between MAP sensor connector and PCM connector. Clear DTCs, and repeat QUICK TEST .

  13. 13) Check SIG RTN Circuit Continuity

    Measure resistance between test pin No. 34 at breakout box and Gray/Red wire at MAP sensor wiring harness connector. If resistance is less than 5 ohms, replace PCM. Clear DTCs, and repeat QUICK TEST . If resistance is 5 ohms or more, locate and repair open in Gray/Red wire. Clear DTCs, and repeat QUICK TEST .

  14. 14) Check For Short To Power

    Disconnect PCM 104-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Measure voltage between ground and test pin No. 90 at breakout box. If voltage is less than .25 volt, replace PCM. Clear DTCs, and repeat QUICK TEST . If voltage is .25 volt or more, locate and repair short to power in VREF circuit. Clear DTCs, and repeat QUICK TEST .

  15. 15) KOEO DTC 0238

    DTC 0238 indicates high input in turbo boost sensor circuit. Possible causes for this DTC are:
    • Faulty MAP sensor.
    • Faulty PCM.

    Disconnect MAP sensor connector. Connect MAP sensor tester between MAP sensor and MAP sensor wiring harness connector. Connect banana plugs of tester into DVOM. Set DVOM to frequency scale. Turn ignition on. If frequency is more than 125 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST. If frequency is 125 Hz or less, replace PCM. Clear DTCs, and repeat QUICK TEST .

  16. 16) Continuous Memory DTC 0237 Or 0235

    Continuous Memory DTC 0237 indicates low input to turbo boost sensor. DTC 0235 indicates MAP sensor signal is inactive. Possible causes for these faults are:
    • Faulty MAP sensor.
    • Open or shorted wiring harness circuits.
    • Faulty PCM.

    Turn ignition off. Disconnect MAP sensor connector. Connect MAP sensor tester between MAP sensor and MAP sensor wiring harness connector. Connect banana plugs of tester into DVOM. Set DVOM to frequency scale. Turn ignition on. If frequency is 105-115 Hz, go to next step. If frequency is not 105-115 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST .

  17. 17) Check MAP Sensor

    While observing DVOM frequency, tap on sensor to simulate road shock. Wiggle sensor connector. If no change in frequency occurs, go to next step. If any change in frequency occurs, locate and repair intermittent open in Gray/Red wire. Clear DTCs, and repeat QUICK TEST .

  18. 18) MAP Sensor Pressure

    Check Disconnect MAP sensor vacuum hose. Using Pressure Adapter (014-00761), apply 10 psi to MAP sensor. While observing DVOM, tap on sensor to simulate road shock. Wiggle sensor connector. If no change in frequency occurs, go to next step. If any change in frequency occurs, replace MAP sensor. Clear DTCs, and repeat QUICK TEST .

  19. 19) Check SIG RTN Circuit

    Remove MAP sensor tester. Leave MAP sensor disconnected. Connect DVOM between ground and Gray/Red wire at MAP sensor wiring harness connector. Set DVOM to ohms scale. While observing DVOM, wiggle and bend small sections of wiring harness starting at MAP sensor wiring harness connector and working toward PCM. If fault is indicated (resistance fluctuates), repair intermittent open circuit in Gray/Red wire. Clear DTCs, and repeat QUICK TEST . If no fault is found, go to next step.

  20. 20) Check VREF Circuit

    Turn ignition on. Connect DVOM between ground and Brown/White wire at MAP sensor wiring harness connector. Set DVOM to volt scale. While observing DVOM, wiggle and bend small sections of wiring harness starting at MAP sensor wiring harness connector and working toward PCM. If fault is indicated (voltage fluctuates), locate and repair intermittent open circuit in Brown/White wire. Clear DTCs, and repeat QUICK TEST . If no fault is found, go to next step.

  21. 21) Check MAP Sensor Signal Circuit Continuity

    Turn ignition off. Disconnect PCM 104-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Disconnect MAP sensor connector. Measure resistance between test pin No. 34 and Light Green/Black wire at MAP sensor wiring harness connector. Resistance should be less than 5 ohms. While observing DVOM, wiggle and bend small sections of wiring harness starting at MAP sensor wiring harness connector and working toward PCM. If resistance stays at less than 5 ohms, go to next step. If resistance does not stay at less than 5 ohms, locate and repair intermittent open circuit in Light Green/Black wire. Clear DTCs, and repeat QUICK TEST .

  22. 22) Check For Short To Ground

    Measure resistance between test pin No. 34 and test pins No. 25, 51, 76, 77 and 103 at breakout box. While observing DVOM, wiggle and bend small sections of wiring harness starting at MAP sensor wiring harness connector and working toward PCM. If all readings are more than 10 k/ohms, go to next step. If any reading is less than 10 k/ohms, locate and repair intermittent short to ground in Light Green/Black wire. Clear DTCs, and repeat QUICK TEST .

  23. 23) Check For Short To Power

    Turn ignition on. Measure voltage between ground and test pin No. 34 at breakout box. While observing DVOM, wiggle and bend small sections of wiring harness starting at MAP sensor wiring harness connector and working toward PCM. If voltage stays at zero volts, fault cannot be duplicated at this time and testing is complete. If voltage does not stay at zero volts, locate and repair intermittent open circuit in Light Green/Black wire. Clear DTCs, and repeat QUICK TEST .

  24. 24) Continuous Memory DTC 0238

    Continuous Memory DTC 0238 indicates high input to turbo boost sensor circuit. Possible causes for this DTC are:
    • Faulty MAP sensor.
    • Open or shorted wiring harness circuits.
    • Faulty PCM.

    Turn ignition off. Disconnect MAP sensor connector. Connect MAP sensor tester between MAP sensor and MAP sensor wiring harness connector. Connect banana plugs of tester into DVOM. Set DVOM to frequency scale. Turn ignition on. Observe DVOM and tap on MAP sensor to simulate road shock. If frequency reading changes to more than 125 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST . If frequency reading does not change to more than 125 Hz, go to next step.

  25. 25) Check MAP Sensor

    Disconnect MAP sensor vacuum hose. Using Pressure Adapter (014-00761), apply 10 psi to MAP sensor. While observing DVOM, tap on sensor to simulate road shock. Wiggle sensor connector. If frequency reading changes to more than 300 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST . If frequency reading does not change to more than 300 Hz, fault cannot be duplicated at this time and testing is complete.

  26. 26) MAP Harness Check

    Using a vacuum pump from Rotunda Pressure Adapter Kit (014-00761) or equivalent, apply 10 in. of vacuum. Observe frequency reading while performing the following:
    • Grasp the vehicle harness close to the sensor connector.
    • Wiggle and shake the vehicle while working towards the PCM.

    If frequency reading goes above 300 Hz, repair intermittent circuit failure. Clear DTCs and repeat QUICK TEST . If frequency reading does not go above 300 Hz, failure is intermittent. Unable to duplicate at this time. Clear DTCs, and repeat QUICK TEST .

  27. 27) KOEO DTC 0237 (1995 Model)

    DTC 0237 indicates low input to turbo boost sensor circuit. Possible causes for this DTC are:
    • Faulty MAP sensor.
    • Faulty PCM.

    Turn ignition off. Disconnect MAP sensor connector. Using Flex Probes from New Generation Star (NGS) tester, jumper VREF and SIG RTN circuits from wiring harness connector to MAP sensor connector. Connect a jumper wire between Light Green/Black wire at MAP sensor connector to SIG INPUT on NGS tester. Select frequency meter. Use 4-volt DC scale. Turn ignition on. If frequency reading is 95-125 Hz, replace PCM. Clear DTCs, and repeat QUICK TEST . If frequency reading is not 95-125 Hz, replace MAP sensor. Clear DTCs, and repeat QUICK TEST .

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