P0685 Auto Shutdown Relay Control Circuit

P0685 code - This diganostic runs when the ignition is turned off, during after-run mode operation. The Powertrain Control Module (PCM) determines that the ASD relay has shut off before the AFTER-RUN mode of operation has been completed. This is a non MIL fault.

Possible causes P0685 code

- ASD relay control circuit shorted to voltage
- ASD relay control circuit shorted to ground
- ASD relay control circuit open/high resistance
- Loss of Powertrain Control Module power or grounds
- ASD relay
- Powertrain Control Module (PCM)

Diagnose P0685 code

Step 1. Check for other DTCs
Turn the ignition on, with the scan tool check for additional DTCs.

Are other DTCs present?

Yes, perform the diagnostics for the other DTCs before continuing.
No, go to step 2.

Step 2. Clear code and check the DTC resets
With the scan tool, erase DTCs. Perform the several ignition key cycles, pausing for at least 10 seconds between each cycle. Turn the ignition on, with the scan tool read PCM DTCs.

Did this DTC return?

Yes, go to step 3.
No, perform the PCM intermittent condition.

Step 3. Subtitute the ASD relay
Turn the ignition off, install a known good relay in place of the ASD relay. Turn the ignition on with the scan tool erase PCM DTCs. Perform several ignition key cycles, pausing for at least 10.0 seconds between each cycle. Turn the ignition on, with the scan tool read PCM DTCs.

Did this DTC return?

Yes, go to step 4.
No, replace the ASD relay.

Step 4. Check PCM power and grounds
Using the wiring diagram information, check the PCM battery, ignition feed and ground circuits.

Were any problem found with the PCM powers and grounds?

Yes, repair as necessary.
No, go to step 5.

Step 5. Check the ASD relay control circuit for a short to voltage
Reconnect the PCM harness connectors, turn the ignition off, remove the ASD relay. Turn the ignition on, measure the voltage an the ASD relay control circuit at terminal 85 of the ASD relay connector.

Is there any voltage present?

Yes, repair the ASD relay control circuit for a short to voltage.
No, go to step 6.

Step 6. Check the ASD relay control circuit for a short to ground
Turn the ignition off, remove the ASD relay. Disconnect the PCM c1 harness connector, measure the resistance an the ASD relay control circuit at terminal 85 of the ASD relay connector.

Is the resistance above 10k Ohms?

Yes, go to step 7.
No, repair the ASD relay control circuit for a short to ground.

Step 7. Check the ASD relay control circuit for an open/high resistance
Measure the resistance of the ASD relay control circuit between the PCM C1 harness connector and the ASD relay connector.

Is the resistance below 5.0 Ohms?

Yes, repair the ASD relay control circuit for an open or high resistance.
No, replace and program the Powertrain Control Module (PCM), perform the Powertrain Verification Test.

Test complete.

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