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Diagnostic Aids

WARNING: This page is about a different car, the 1996 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

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

Fig 1: WAC Test Circuits & Connector Terminals
G95A27227
  1. Step 1) DTC P1460: Verify ACCS PID Is Off  Turn ignition off. Ensure A/C and defroster are off. Connect scan tester to Data Link Connector (DLC). Start engine and allow to idle. Using scan tester, access ACCS PID. If ACCS PID is off, go to next step. If ACCS PID is on, go to step 20).
  2. Step 2) Check VPWR Circuit  Turn ignition off. Disconnect WAC relay wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at connector and chassis ground. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in VPWR circuit. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  3. Step 3) Check WAC Relay  Leave ignition off and WAC relay disconnected. Check resistance between relay terminals No. 85 and 86.

    Replace WAC relay if resistance is not 40-120 ohms. If resistance is okay, check resistance between relay terminals No. 85 and 30, No. 85 and 87, No. 85 and 87A.

    If resistance is okay, go to next step. If resistance less than 10,000 ohms, replace WAC relay. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .

    Fig 2: WAC Relay Connector Terminals
    G96D01039
  4. Step 4) Check WAC Circuit  Turn ignition off. Leave WAC relay disconnected. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 69 (WAC) at breakout box and chassis ground. If voltage less than one volt, go to next step. If voltage one volt or more, repair circuit short to power. Start engine, allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  5. Step 5) Turn ignition off. Disconnect scan tester from DLC (if applicable). Measure resistance between test pin No. 69 (WAC) and test pins No. 51, 91 and 103 (PWR GND) at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair circuit short to ground. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  6. Step 6) Leave ignition off and relay disconnected. Measure resistance between breakout box test pin No. 69 and WAC terminal at relay connector. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST . If resistance is 5 ohms or more, repair open circuit. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 10). No test procedures have been omitted.
  7. Step 10) Check For Voltage To A/C Cycling Switch  Turn ignition off. Disconnect A/C cycling switch. Turn A/C switch on. Measure voltage between chassis ground and A/C Demand terminal or A/C cycling switch. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check for fault in A/C demand switch, EATC module or related wiring harness. See the A/C-HEATER SYSTEM - MANUAL article.
  8. Step 11) Check For Voltage To A/C Pressure Switch (ACPSW)  Turn ignition off. Reconnect A/C cycling switch. Disconnect ACPSW. Turn A/C switch on. Measure voltage between chassis ground and A/C Demand terminal at the ACPSW wiring harness connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check for fault in A/C demand switch, EATC module or related wiring harness. See the A/C-HEATER SYSTEM - MANUAL article.
    Fig 3: ACPSW Connector Terminals
    G96F01040
  9. Step 12) Check Continuity Of ACPSW Contacts  Turn ignition off. Leave A/C switch on. Measure resistance between ACPSW high pressure contacts. If resistance is less than 5 ohms, reconnect ACPSW and go to next step. If resistance is 5 ohms or more, check for over-pressurized A/C system. If system pressure is okay, replace ACPSW and verify symptom is corrected.
  10. Step 13) Check For Voltage To PCM  Leave A/C switch on. Turn ignition off. Reconnect ACPSW. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pin No. 77 (PWR GND) at breakout box. If voltage is one volt or more, repair open circuit between ACPSW and PCM. If voltage is more than 10.5 volts, replace PCM and verify symptom is corrected.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 19). No test procedures have been omitted.
  11. Step 19) DTC P1464: Check ACCS PID  Turn ignition off. Ensure A/C and defroster are off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is on, go to next step. If ACCS PID is off, verify self-test results. Leave A/C and defroster off and repeat QUICK TEST .
  12. Step 20) Turn ignition off. Disconnect ACPSW. Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is off, check for fault in A/C demand switch, EATC module or related wiring harness. See the A/C-HEATER SYSTEM - MANUAL article. If ACCS PID is on, go to next step.
  13. Step 21) Check For Short To Power  Turn ignition off. Disconnect WAC relay. Turn ignition on. Measure voltage between chassis ground and POWER-TO-CLUTCH terminal of WAC relay connector. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair circuit short to power. Verify symptom is corrected.
  14. Step 22) Check ACCS Circuit For Short To Power  Turn ignition off. Leave ACPSW and WAC relay disconnected. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pins No. 51 and 103 (PWR GND) at breakout box. If voltage is more than one volt, repair circuit short to power. If voltage is one volt or less, proceed as follows:
    • For vehicle without WAC relay, replace PCM and repeat QUICK TEST .
    • For all other models, go to next step.
  15. Step 23) Check ACCS Circuit Voltage To PCM  Turn ignition off. Reconnect WAC relay. Leave ACPSW disconnected. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pins No. 51 and 103 (PWR GND) at breakout box. If voltage is more than one volt, replace WAC relay and verify symptom is corrected. If voltage is one volt or less, replace PCM and verify symptom is corrected.
    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.
  16. Step 30) Continuous Memory DTC P1460  This DTC indicates WAC circuit failure. If vehicle is not equipped with A/C, disregard this DTC. Turn ignition off. Disconnect A/C cycling switch or low pressure switch. Connect jumper wire between switch terminals. Turn ignition and A/C switch on. Check for indication of fault while wiggling and bending WAC circuit between WAC relay and PCM. Fault will be indicated by A/C clicking on. Wiggle and bend WAC circuit between PCM (terminal No. 69) and WAC relay. Lightly tap on WAC relay. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. If no faults are found, go to next step.
  17. Step 31) Turn ignition off. Connect scan tester to Data Link Connector (DLC). Leave ignition and A/C switch on. Turn ignition on. Using scan tester, access Output Test Mode. Turn all outputs off. Check for indication of fault while wiggling and bending WAC or ACON circuit between PCM (terminal No. 69) and WAC and A/C relay. Fault will be indicated by A/C clicking on. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. If no faults are found, fault 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 31) to step 50). No test procedures have been omitted.
  18. Step 50) KOEO Or KOER DTC P1460: Check Voltage To A/C Relay  This DTC indicates A/C relay primary circuit failure. If A/C or defrost were on during self test, clear PCM memory, repeat QUICK TEST . Turn ignition off. Disconnect A/C relay. Turn ignition off. Disconnect A/C relay. Measure voltage between chassis ground and IGN RUN terminal of A/C relay connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check for damaged fuse. If fuse is okay, repair open in circuit.
    Fig 4: A/C Relay Connector Terminals
    G96H01041
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 50) to step 61). No test procedures have been omitted.
  19. Step 61) Check ACON Circuit For Short To Power  Turn ignition off. Leave A/C relay disconnected. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between chassis ground and test pin No. 69 (ACON) at breakout box. If voltage is one volt or less, go to next step. If voltage is more than one volt, repair circuit short to power. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  20. Step 62) Check ACON Circuit For Short To Ground  Turn ignition off. Disconnect scan tester from DLC (if applicable). Measure resistance between chassis ground and test pin No. 69 (WAC) at breakout box. If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, repair circuit short to ground. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  21. Step 63) Check ACON Circuit Continuity  Leave ignition off and relay disconnected. Measure resistance between breakout box test pin No. 69 and ACON terminal at A/C relay connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .
  22. Step 64) Check A/C Relay  Leave ignition off. Reconnect A/C relay. Disconnect A/C clutch. Connect voltmeter between A/C clutch terminals. Turn ignition on. Voltage should be less than 1.0 volt. Connect jumper wire between ground and breakout box test pin No. 69 (ACON). Voltage should be more than 10.5 volts.

    If voltage is as specified, reconnect all components. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST . If DTC P1460 is still present, replace PCM.

    If voltage is not as specified, replace A/C relay. Reconnect all components. Start engine and allow to idle for 15 seconds with A/C on. Turn ignition and A/C off. Repeat QUICK TEST .

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 64) to step 70). No test procedures have been omitted.
  23. Step 70) DTC P1464: Check ACCS PID  Turn ignition off. Ensure A/C and defroster are off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is off, go to next step. If ACCS PID is on, go to step 72).
  24. Step 71) Check Low Pressure (LP) Switch  Turn ignition off. Disconnect LP switch. Measure resistance between chassis ground and both terminals of LP switch. If resistance is 10,000 ohms or more, check for faulty A/C demand switch. See the A/C-HEATER SYSTEM article. If switch is okay, repair circuit short to ground between LP switch and A/C demand switch. If resistance is less than 10,000 ohms, replace LP switch and verify symptom is corrected.
  25. Step 72) Check Low Pressure (LP) Switch  Leave ignition off and LP switch disconnected. Disconnect PCM wiring harness connector. Measure resistance between chassis ground and PCM side of LP switch. If resistance is 10,000 ohms or more, replace PCM and verify symptom is corrected. If resistance is less than 10,000 ohms, repair short to ground and verify symptom is corrected.
  26. Step 73) Leave ignition off and LP switch disconnected. Disconnect A/C relay. Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is on, go to next step. If ACCS PID is off, go to step 76).
  27. Step 74) Leave ignition off, A/C relay and LP switch disconnected. Disconnect WAC relay. Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is on, go to next step. If ACCS PID is off, repair POWER-TO-CLUTCH circuit short to power.
  28. Step 75) Check ACCS & A/C DEMAND Circuit For Short To Power  Turn ignition off. Leave A/C relay, LP switch and WAC relay disconnected. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between chassis ground and test pin No. 41 (ACCS) at breakout box. If voltage is one volt or less, replace PCM and verify symptom is corrected. If voltage is more than one volt, repair circuit short to power and verify symptom is corrected.
  29. Step 76) Check A/C DEMAND Circuit For Short To Ground  Turn ignition off. Disconnect scan tester from DLC (if applicable). Measure resistance between chassis ground and A/C DEMAND terminal at LP switch. If resistance is 10,000 ohms or more, replace LP switch and verify symptom is corrected. If resistance is less than 10,000 ohms, repair circuit short to ground and verify symptom is corrected.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 76) to step 100). No test procedures have been omitted.
  30. Step 100) Check WAC Relay Contacts  Turn ignition off. Disconnect WAC relay wiring harness connector. Measure resistance between terminals No. 3 and 4. See Fig 2 If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, replace WAC relay and verify symptom is corrected.
  31. Step 101) Check Voltage To A/C Clutch Relay  Turn ignition off. Disconnect A/C clutch relay. Turn ignition on. Measure voltage between negative battery terminal and IGN RUN terminal of A/C relay connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check system fuse. If fuse is okay, repair open circuit and verify symptom is corrected.
  32. Step 102) Check A/C Clutch Relay Ground Circuit  Turn ignition off. Leave A/C clutch relay disconnected. Measure resistance between negative battery terminal and ground terminal of relay connector. See Fig 1 If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and verify symptom is corrected.
  33. Step 103) Leave ignition off and A/C clutch relay disconnected. Disconnect A/C clutch. Disconnect scan tester (if applicable). Measure resistance of POWER-TO-CLUTCH circuit between A/C clutch connector and A/C relay connector. Measure resistance of ground circuit between A/C clutch connector and negative battery terminal. If both resistance measurements are less than 5 ohms, replace A/C clutch relay and verify symptom is corrected. If resistance is 5 ohms or more, repair open circuit and verify symptom is corrected.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 103) to step 110). No test procedures have been omitted.
  34. Step 110) Check ACCS PID  Turn ignition off. Leave ACPSW disconnected. Disconnect A/C clutch relay. Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is off, replace A/C clutch relay and verify symptom is corrected. If ACCS PID is on, go to next step.
  35. Step 111) Check ACCS PID  Turn ignition off. Leave A/C clutch relay and ACPSW disconnected. Disconnect WAC relay. Turn ignition on. Using scan tester, access ACCS PID. If ACCS PID is off, replace WAC relay and verify symptom is corrected. If ACCS PID is on, go to next step.
  36. Step 112) Check ACCS Circuit To PCM For Short To Power  Turn ignition off. Leave ACPSW, A/C relay and WAC relay disconnected. Disconnect PCM wiring harness connector. Inspect connector for damage or corrosion, and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 (ACCS) and test pins No. 51 and 103 (PWR GND) at breakout box. If voltage is more than one volt, repair circuit short to power and verify symptom is corrected. If voltage is one volt or less, replace PCM and verify symptom is corrected.
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