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Home >> Ford >> 1996 >> Probe Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.0L >> Circuit Tests >> Circuit Test DK - Misfire Detection (MD) Sensor >> Diagnostic Aids

Diagnostic Aids

Perform this test only when directed by QUICK TEST . This test is intended to diagnose the following:

Fig 1: MD Test Circuits & Connector Terminals
G95J35948
  1. Step 1) DTC P0385  DTC P0385 indicates that self-test has detected a MD sensor/circuit failure. Possible causes for these faults are:
    • Wiring harness open (MD or SIG RTN).
    • MD circuit shorted to power or ground.
    • Faulty MD sensor.
    • Powertrain Control Module (PCM).

    If engine will start, go to next step. If engine will not start, no-start condition has caused DTC P0385. Service or repair as necessary and repeat QUICK TEST .

  2. Step 2) Check For Intermittent Circuit Fault  Clear all DTCs from PCM memory. Start engine and raise speed to 1500 RPM for 10 seconds 3 times. Turn ignition off. Connect scan tester to DLC. Using scan tester, retrieve all Continuous Memory DTCs. If DTC P0385 is present, go to step 5). If DTC P0385 is not present, fault is intermittent and cannot be duplicated at this time. Go to CIRCUIT TEST Z.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 5). No test procedures have been omitted.
  3. Step 5) Check Circuit Continuity  Turn ignition off. Disconnect MD wiring harness connector. Disconnect PCM 104-pin connector. Inspect connector for damaged and repair as necessary. Install EEC-V Breakout Box (014-00950), leaving PCM disconnected. Measure resistance of MD circuit between wiring harness connector terminal and test pin No. 59 at breakout box. Measure resistance of SIG RTN circuit between wiring harness connector terminal and test pin No. 91 at breakout box. If either resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
  4. Step 6) Check MD Circuit For Short To Power  Leave MD sensor and PCM disconnected. Turn ignition on. Measure voltage between test pin No. 59 (MD) and test pins No. 51 and 103 (PWR GND) at breakout box. If both voltage measurements are 1.0 volt or less, go to next step. If either voltage measurement is more than 1.0 volt, repair circuit short to power and repeat QUICK TEST .
  5. Step 7) Check MD Circuit For Short To Ground  Leave MD sensor and PCM disconnected. Turn ignition off. Measure resistance between test pin No. 59 (MD) and test pins No. 51, 103 (PWR GND) and 91 at breakout box. If each resistance measurement is 10,000 ohms or more, go to next step. If either resistance measurement less than 10,000, repair circuit short, repeat QUICK TEST .
  6. Step 8) Check For Short In PCM  Leave ignition off and MD sensor disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 59 (MD) and test pins No. 23 (IGN GND), 51, 103 (PWR GND), 71 and 97 (VPWR) and 91 (SIG RTN) at breakout box. If each resistance measurement is 500 ohms or more, go to next step. If either resistance measurement is less than 500 ohms, replace PCM and repeat QUICK TEST .
  7. Step 9) Check For Short In PCM  Leave ignition off and PCM disconnected. Reconnect MD sensor. Set voltmeter on AC scale. Start engine and allow to idle. With engine idling, measure voltage between test pin No. 59 (MD) and test pins No. 51 and 103 (PWR GND) at breakout box. If AC voltage varies more than 0.1 volt, replace PCM and repeat QUICK TEST . If AC voltage does not vary more than 0.1 volt, go to next step.
  8. Step 10) Check MD Sensor Trigger Wheel  Turn ignition off. Inspect MD sensor trigger wheel for damage. Ensure trigger wheel is not loose or misaligned. Service or repair as necessary and repeat QUICK TEST. If trigger wheel is okay, replace MD sensor and repeat QUICK TEST .
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