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Home >> Mazda >> 1999 >> B2500 SX, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics - EEC-V - 6.8L (99S E Series & 99S F350 To F550)) >> System Tests >> Test KP: Charge Air Cooler Pump (CAC) >> Diagnostic Aids

Diagnostic Aids

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Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

  1. 1) DTC P1229: Check Power To CAC Pump Relay Coil

    Turn ignition off. Check fuse No. 23. If fuse is okay, go to next step. If fuse is blown, check circuits No. 391 and No. 369 for short to ground. Repair as necessary. Replace blown fuse.

  2. 2) Check Power To CAC Pump Relay

    Check fuse No. 106. If fuse is okay, go to next step. If fuse is blown, check circuits No. 17 and No. 18 for short to ground. Repair as necessary. Replace blown fuse.

  3. 3) Check CAC Pump Ground Circuit

    Disconnect CAC pump motor connector. Measure resistance between chassis ground terminal at CAC pump motor wiring harness connector and negative battery terminal. See Fig 1. If resistance is less than 2 ohms, go to next step. If resistance is 2 ohms or more, check tightness of ground lug. If ground lug is okay, check for open ground circuit.
    Fig 1: Identifying Charge Air Cooler Pump Motor Wiring Harness Connector Terminals
    G99F02662Courtesy of FORD MOTOR CO.

  4. 4) Check CAC Pump Motor Resistance

    Measure resistance between CAC pump motor terminals. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, replace CAC pump motor.

  5. 5) Check CAC Pump Relay

    Remove CAC pump motor relay from engine compartment power distribution box. Measure resistance between relay terminal No. 1 and all other relay terminals. Resistance should be 65-90 ohms between terminals No. 1 and 2 and more than 10,000 ohms between terminal No. 1 and all other relay terminals. See Fig 2. If resistance is as specified, go to next step. If resistance is not as specified, replace relay.
    Fig 2: Identifying Charge Air Cooler Pump Motor Relay Wiring Harness Connector Terminals
    G99F02662Courtesy of FORD MOTOR CO.

  6. 6) Check For Open Circuit

    Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance of CAC circuit between PCM connector and CAC pump motor relay wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in CAC circuit.

  7. 7) Check For Short To Ground

    Measure resistance of CAC circuit between PCM connector and negative battery terminal. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in CAC circuit.

  8. 8) Check For Short To Power

    Turn ignition on. Measure voltage of CAC circuit between PCM connector and negative battery terminal. If voltage is less than .5 volt, go to next step. If voltage is .5 volt or more, repair short to power in CAC circuit.

  9. 9) Check For Open In FUSE 23 Circuit

    Turn ignition off. Remove fuse No. 23. Measure resistance of FUSE 23 circuit between CAC pump motor relay wiring harness connector and fuse holder (output side) for fuse No. 23. See Fig 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FUSE 23 circuit.

  10. 10) Check For Open In FUSE 106 Circuit

    Turn ignition off. Remove fuse No. 106. Measure resistance of FUSE 106 circuit between CAC pump motor relay wiring harness connector and fuse holder (output side) for fuse No. 106. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FUSE 106 circuit.

  11. 11) Check CAC Circuit Resistance

    Measure resistance of CAC circuit between CAC pump motor relay wiring harness connector and CAC pump motor wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in CAC circuit.

  12. 12) Check SCICP PID

    Turn ignition on. Using scan tool, select SCICP PID from PID/DATA monitor menu. If PID value indicates OFF, no problem is indicated at this time. Go to TEST Z  and check for intermittent faults. If PID value indicates ON, proceed as follows:
    • Check CAC reservoir level,
    • Check for air flow blockage at CAC intercooler.
    • Check for high resistance or open circuit in Intake Air Temperature (IAT) 2 sensor and connecting circuits.

    Repair as necessary. If no problems are found and DTC P1229 is present in KOEO and KOER, replace PCM.

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