Diagnostic Aids

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

• Wiring harness circuits (ACCS, POWER-TO-CLUTCH, VPWR and WAC).
• Faulty WAC relay.
• Faulty Powertrain Control Module (PCM).

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

   
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 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 A/C-HEATER SYSTEM - MANUAL article.
   Fig 3: ACPSW Connector Terminals

   
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 A/C-HEATER SYSTEM - MANUAL article. If ACCS PID is on, go to step 22).
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