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, ACPSW, VPWR & WAC), See Fig 1-Fig 3
- Faulty Wide Open Throttle A/C Cut-off (WAC) Relay
- Faulty Powertrain Control Module (PCM)
| Application | Location |
|---|---|
| All Models | In Battery Junction Box, In Engine Compartment |
- 1) KOEO & KOER DTC P1460: Verify ACCS PID Is Off
This DTC indicates an excessive current draw when PCM grounds Wide Open Throttle A/C Cut-off (WAC) circuit, or voltage is not detected on WAC circuit when PCM interrupts ground on WAC circuit. Possible causes are:- A/C Or Defroster On During Self-Test
- Open Or Shorted WAC Circuit
- Faulty WAC Relay
- Open VPWR Circuit To WAC Relay
- Faulty PCM
Ensure A/C and defroster were off during KOEO and/or KOER ON-DEMAND SELF-TEST. If A/C or defroster was on during self-test, turn system off and repeat self-test. If vehicle is equipped with A/C, start engine and allow to idle. Using scan tool, select ACCS PID from PID/DATA MONITOR & RECORD menu. If ACCS PID value indicates OFF, go to next step. If ACCS PID value indicates ON, ACCS input to PCM is requesting A/C, see appropriate A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- 2) Check VPWR Voltage To WAC Relay
Turn ignition switch to OFF position. Remove WAC relay. For WAC relay locations, refer to WIDE OPEN THROTTLE A/C CUTOFF RELAY LOCATIONS table. Turn ignition switch to ON position. Using a DVOM, measure voltage between ground and WAC relay VPWR cavity . See Fig 1. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR (IGN RUN on Continental) circuit. See A/C wiring diagram in appropriate A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. - 3) Check WAC Relay
Turn ignition switch to OFF position and proceed as follows:- ISO Micro Relay
Measure resistance between relay terminal No. 1 and 2. Resistance should be 40-120 ohms. Measure resistance between terminals No. 1 and all other relay terminals. Resistance should be more than 10 k/ohms. - ISO Mini Relay
Measure resistance between relay terminal No. 85 and 86. Resistance should be 40-120 ohms. Measure resistance between terminals No. 85 and all other relay terminals. Resistance should be more than 10 k/ohms. See Figure.
On either relay, if resistance is as specified, go to next step. If relay resistance is not as specified, replace WAC relay.
- ISO Micro Relay
- 4) Check WAC Circuit For Short To VPWR In Harness
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using a DVOM, measure voltage between ground and WAC ISO micro relay cavity No. 1, or WAC ISO mini relay cavity No. 85. See Figure. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to VPWR in WAC circuit. - 5) Check WAC Circuit For Short To Ground In Harness
Turn ignition switch to OFF position. Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between ground and WAC ISO micro relay cavity No. 1, or WAC ISO mini relay cavity No. 85. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in WAC circuit. - 6) Check WAC Circuit For Open In Harness
Using a DVOM, measure resistance of WAC circuit between PCM harness connector and WAC relay cavity No. 1 (ISO micro), or cavity No. 85 (ISO mini). See Fig 1. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in WAC circuit.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. - 10) ACCS PID OFF With A/C On: Check For VPWR To A/C Clutch
Disconnect A/C clutch connector. Connect test light between A/C clutch harness connector terminals. Start engine. Turn A/C on. If test light illuminates, VPWR is being supplied to A/C clutch, but ACCS PID value reads OFF. Go to next step. If test light does not illuminate, ACCS PID is OFF due to VPWR not being supplied to A/C clutch. A/C clutch is not cause of low idle symptom. Return to SYMPTOMS in TROUBLE SHOOTING - NO CODES article to diagnose low idle problem. Repair as necessary. If low idle is not a problem and A/C clutch does operate, see appropriate A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. - 11) Check ACCS Circuit For Open In Harness
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of ACCS circuit between PCM harness connector terminal No. 41 and A/C clutch harness connector. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open circuit in ACCS circuit between A/C clutch and PCM.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 11) to step 19). No test procedures have been omitted. - 19) KOEO & KOER DTC P1464: Check ACCS PID
This DTC indicates ACCS input to PCM was high during self-test. Possible causes for this fault are:- A/C On During Self-Test
- Short To VPWR In A/C Clutch VPWR Circuit (Applications With Normally Closed WAC Relay)
- Short To VPWR In ACCS Circuit
- Faulty A/C Demand Switch
- Faulty WAC Relay
- Faulty PCM
Ensure both A/C and defroster were off during KOEO ON-DEMAND SELF-TEST and KOER ON-DEMAND SELF-TEST. If either A/C or defroster were on during self-test, turn system off and repeat self-test. If ACCS PID value indicates ON, ACCS input to PCM is requesting A/C. Go to appropriate A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING to diagnose A/C always ON symptom. If ACCS PID value indicates OFF, this indicates that ACCS input to PCM is low. Verify self-test results. Leave A/C and defroster off and repeat QUICK TEST .
- 30) Continuous Memory DTC P1460: Check WAC Circuit For Intermittent Short To Ground
This DTC indicates an excessive current draw when PCM grounds Wide Open Throttle A/C Cut-Off (WAC) circuit, or voltage is not detected on WAC circuit when PCM interrupts ground on WAC circuit. Possible causes are:- A/C Or Defroster On During Self-Test
- Open Or Shorted WAC Circuit
- Faulty WAC Relay
- Open VPWR Circuit To WAC Relay
- Faulty PCM
Turn ignition and A/C switch on. Check WAC circuit for short to ground (fault will be indicated by A/C clicking on) while performing the following:
- Shake, wiggle and bend WAC circuit between PCM and WAC relay. See Fig 1.
- Lightly tap on WAC relay to simulate road shock.
If any faults are found, isolate fault and repair as necessary. If no faults are found, go to next step.
- 31) Check WAC Circuit For Intermittent Open Or Short To VPWR
Ensure ignition switch is turned to ON position. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. Command ALL OUTPUTS ON. Check WAC circuit for open or short to VPWR (fault will be indicated by A/C clicking off) while performing the following:- Shake, wiggle and bend WAC circuit between PCM and WAC relay.
- Shake, wiggle and bend VPWR circuit to WAC relay.
- Lightly tap on WAC relay to simulate road shock.
If any faults are found, isolate fault and repair as necessary. Perform KEEP ALIVE RANDOM ACCESS MEMORY RESET PROCEDURE under CLEARING CODES. If no faults are found, fault cannot be duplicated at this time. Go to TEST Z, step 1).