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Diagnostic Aids

Perform this test when directed by QUICK TEST. To prevent replacing good components, check the following non-EEC components and systems

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  1. 1) DTC P1460: (KOEO/KOER) Check ACCS PID Is Off  DTC P1460 indicates A/C was on during SELF-TEST or a WAC fault. Possible causes for this fault are:
    • A/C on during self-test.
    • Open or shorted circuit.
    • Faulty WAC relay.
    • Faulty PCM.

    If A/C or defrost was on during KOEO/KOER SELF-TEST, turn A/C off and repeat QUICK TEST. If A/C was not on, start engine. Using scan tool access ACCS PID. If ACCS PID is off, go to next step. If ACCS PID is on, go to step 20).

    Fig 1: WOT A/C Cut-Out Circuit (Aerostar)
    G96F04232
    Fig 2: WOT A/C Cut-Out Circuit (Explorer & Ranger)
    G96H04233
  2. 2) Check For VPWR To WAC Relay  Turn ignition off. Remove WAC relay. Turn ignition on. Measure voltage between VPWR relay connector terminal and chassis ground. If voltage is more than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open VPWR circuit. Install WAC relay and repeat QUICK TEST.
    Fig 3: WAC Relay Connector Terminals
    G96D01039
  3. 3) Check WAC Relay  Turn ignition off. Remove WAC relay. Measure resistance between relay terminal No. 85 and 86. Resistance should be 40-85 ohms. Measure resistance between terminal No. 85 and terminals No. 30, 87 and 87A. Resistance should be 10 k/ohms or more. If resistance is as specified, go to next step. If resistance is not as specified, replace WAC relay. Repeat QUICK TEST.
  4. 4) Check WAC Circuit For Short To Power  Ensure ignition is off and WAC relay is removed. Disconnect 104-pin PCM connector. Inspect terminals, and repair if damaged. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 69 and chassis ground. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair short to power in WAC circuit. Connect all components and repeat QUICK TEST.
  5. 5) Check WAC Circuit For Short To Ground  Ensure ignition is off. Disconnect scan tool from DLC. Measure resistance between test pin No. 69 and test pins No. 51, 91, and 103. If each resistance is 10 k/ohms or more, go to next step. If any resistance is less than 10 k/ohms, repair short to ground in WAC circuit. Connect all components and repeat QUICK TEST.
  6. 6) Check WAC Circuit Continuity  Ensure ignition is off. Measure resistance between WAC circuit relay connector terminal and test pin No. 69. If resistance is more than 5 ohms, repair open circuit. Connect all components and repeat QUICK TEST. If resistance is less than 5 ohms, replace PCM. Connect all components and repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 20). No test procedures have been omitted.
  7. 20) ACCS PID On: Disconnect ACPSW & Check ACCS PID Is Off  Turn ignition off. Disconnect A/C pressure switch. Turn ignition on. Using scan tool access ACCS PID. If ACCS PID is on, go to next step. If ACCS PID is off, turn ignition off. Check operation of A/C demand switch or EATC module. If switch is okay, repair short to power in A/C demand circuit to A/C pressure switch.
  8. 21) Check A/C Clutch Circuit For Short To Power  Turn ignition off. Remove WAC relay. Turn ignition on. Measure voltage between power-to-clutch terminal of relay harness connector and chassis ground. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair short to power. Connect all components and repeat QUICK TEST.
  9. 22) Check ACCS Circuit For Short To Power  Ensure ignition is off and WAC relay is removed. Disconnect A/C pressure switch. Disconnect 104-pin PCM connector. Inspect terminals, and repair if damaged. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pins No. 51 and 103. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair short to power in ACCS circuit. Remove breakout box, connect all components and repeat QUICK TEST.
  10. 23) Check ACCS Circuit Voltage To PCM  Turn ignition off. Install WAC relay. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pins No. 51 and 103. If voltage is less than one volt, replace PCM. Remove breakout box, connect all components and repeat QUICK TEST. If voltage is more than one volt, replace WAC relay. Remove breakout box, connect all components and repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 30). No test procedures have been omitted.
  11. 30) DTC P1460: (Continuous Memory) Check WAC Circuit  DTC P01460 indicates WAC circuit failure. Possible causes for this fault are:
    • Open or shorted WAC circuit.
    • Open coil in WAC relay.
    • Open VPWR to WAC relay.
    NOTE: If scan tool will not access PIDs in Output Test Mode, disconnect PCM connector. Install breakout box, reconnect PCM. Connect DVOM to test pin No. 69 (WAC) and test pin No. 71 (VPWR).

    Using scan tool, access Output Test Mode. Access WAC PID and WACA PID (Aerostar and Explorer) or WACF PID (Ranger). Turn WAC and WACF outputs off (DVOM voltage will be above 10 volts). Check for indication of fault while wiggling and bending WAC circuit wiring between relay and PCM. Fault will be indicated by WAC or WACA/WACF PID turning on. If using DVOM, fault will be indicated by voltage drop on DVOM. Wiggle and bend WAC circuit wiring between PCM (terminal No. 69) and relay. Wiggle and bend VPWR circuit wiring between EEC-V power relay and WAC relay. Lightly tap on WAC relay. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. Repeat QUICK TEST. If no faults are found, go to next step.

  12. 31) Check WAC Circuit For Intermittents  Exit Output Test Mode. Access WACA PID (Aerostar and Explorer) or WACF PID (Ranger). Disconnect WAC relay. WACA PID should be on, or WACF should be off. Check for indication of fault while wiggling and bending WAC circuit wiring between PCM (terminal No. 69) and WAC or A/C relay. Fault will be indicated by WACA PID turning off or WACF PID turning on. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. Repeat QUICK TEST. If no faults are found, fault cannot be duplicated at this time. Go to CIRCUIT TEST Z. See appropriate TESTS W/CODES article in ENGINE PERFORMANCE:
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