Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
P0688-ASD RELAY SENSE CIRCUIT LOW DIAGNOSTIC TEST REFERENCE
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 |
NOTE:
Diagnose P0685 - Auto Shutdown Relay Control Circuit first if set along with this DTC. With the DRBIII®, erase the DTC.Attempt to start the engine. If the engine will not start, crank the engine for at least 15 seconds. It may be necessary to repeat several times.Does the DTC reset?Yes --> Go To 2No --> Refer to the INTERMITTENT CONDITION SYMPTOM .Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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| 2 | Attempt to start the engine. Does the engine start? Yes --> Go To 3 No --> Go To 4 |
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| 3 | Turn the ignition off. Remove the ASD Relay from the PDC. Disconnect the C3 PCM harness connector.
CAUTION:
DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance of the (A142) ASD Relay Output circuit from the PDC to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms? Yes --> Go To 8 No --> Repair the open in the (A142) ASD Relay Output circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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| 4 | Turn the ignition off. Install a substitute relay in place of the ASD Relay. Ignition on, engine not running. With the DRBIII®, erase DTCs. Attempt to start the engine. With the DRBIII®, read DTCs. Does the DTC reset? Yes --> Go To 5 No --> Replace the ASD Relay. Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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| 5 | Turn the ignition off. Remove the ASD Relay from the PDC. Using a 12-volt test light connect to ground, probe the (A907) Fused B+ circuits in the PDC. Does the test light illuminate brightly? Yes --> Go To 6 No --> Repair the open or short to ground in the (A907) Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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| 6 | Disconnect the C3 PCM harness connector.
CAUTION:
DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance of the (A142) ASD Relay Output circuit from the PDC to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms? Yes --> Go To 7 No --> Repair the open in the (A142) ASD Relay Output circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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| 7 | Measure the resistance between ground and the (A142) ASD Relay Output circuit at the Relay connection. Is the resistance below 100 ohms? Yes --> Repair the short to ground in the (A142) ASD Relay Output circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 . No --> Go To 8 |
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| 8 |
NOTE:
Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.If there are no possible causes remaining, view repair.RepairReplace and program the Powertrain Control Module per Service Information.Perform POWERTRAIN VERIFICATION TEST VER - 5 . |
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