P0685-ASD/MAIN CONTROL CIRCUIT
For a complete wiring diagram, refer to the Wiring Information.
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When Monitored:
When the ignition is turned on and during after-run mode of operation.
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Set Condition:
The Powertrain Control Module (PCM) determines that the ASD Relay has is stuck on.
Possible Causes |
|---|
| (K51) ASD RELAY CONTROL CIRCUIT OPEN |
| (K51) ASD RELAY CONTROL CIRCUIT SHORTED TO GROUND |
| (K51) ASD RELAY CONTROL CIRCUIT SHORTED TO VOLTAGE |
| ECM POWER AND GROUND CIRCUITS |
| ASD RELAY |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Ignition on, engine not running. |
| 2. | With the scan tool, erase DTCs in the PCM. |
| 3. | Perform several ignition key cycles, pausing for at least one minute between each cycle. |
| 4. | Turn the ignition on. |
| 5. | With the scan tool, select View DTCs. |
Did this DTC return?
Yes
- Go To 2
No
- Perform the INTERMITTENT DTC diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Ignition off. |
| 2. | Install a known good relay in place of the ASD Relay. |
| 3. | Turn the ignition on. |
| 4. | With the scan tool, erase DTCs in the PCM. |
| 5. | Perform several ignition key cycles, pausing for at least one minute between each cycle. |
| 6. | Turn the ignition on. |
| 7. | With the scan tool, select View DTCs. |
Did this DTC return?
Yes
- Go To 3
No
- Repair complete.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
3. CHECKING THE PCM POWER AND GROUND CIRCUITS
| 1. | Turn the ignition off |
| 2. | Install the ASD relay |
| 3. | Perform the diagnostic procedure for CHECKING THE PCM POWER AND GROUND CIRCUITS. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing) . |
Were any problems found?
Yes
- Repair the PCM power and ground circuit(s) as necessary.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 4
4. CHECK FOR THE (K51) ASD RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
| 1. | Reconnect the PCM harness connectors. |
| 2. | Turn the ignition off. |
| 3. | Remove the ASD Relay. |
| 4. | Turn the ignition on. |
| 5. | Measure the voltage on the (K51) ASD Relay Control circuit at terminal 85 of the ASD Relay connector. |
Is there any voltage present?
Yes
- Repair the (K51) ASD Relay Control circuit for a short to voltage.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 5
5. CHECK FOR THE (K51) ASD RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
| 1. | Turn the ignition off. |
| 2. | Disconnect the PCM C2 harness connector. |
| 3. | Measure the resistance between ground and the (K51) ASD Relay Control circuit at terminal 85 of the ASD Relay connector. |
Was the resistance above 10k Ohms?
Yes
- Go To 6
No
- Repair the (K51) ASD Relay Control circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
6. CHECK FOR THE (K51) ASD RELAY CONTROL CIRCUIT FOR AN OPEN
| 1. | Measure the resistance of the (K51) ASD Relay Control circuit between the PCM C2 harness connector and the ASD Relay connector. |
Was the resistance above 10k Ohms?
Yes
- Repair the (K51) ASD Relay Control circuit for an open circuit.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 7
| 1. | Using the wiring diagram/schematic as a guide, inspect the Powertrain Control Module wiring and connectors. |
| 2. | Look for any chafed, pierced, pinched, or partially broken wires. |
| 3. | Look for broken, bent, pushed out or corroded terminals. |
| 4. | Check for proper PCM power supply from the ignition switch and the ASD relay. Check the PCM for proper ground supply. |
| 5. | Perform any Technical Service Bulletins that may apply. |
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Replace the Powertrain Control Module in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).