DTC P0685: Engine Controls Ignition Relay Control Circuit: Troubleshooting
TROUBLESHOOTING CHART
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Perform an ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK . Is the system check complete? | - | Go to Step 2 | Go to ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK |
| 2 | Is DTC P0685 active? | - | Go to Step 3 | Go to Intermittents |
| 3 | 1. Turn the ignition OFF. 2. Remove the main relay. 3. Probe the main relay control circuit terminal at the engine fuse block with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 7 | Go to Step 4 |
| 4 | 1. Turn the ignition ON, with the engine OFF. 2. Probe the engine relay circuit at the engine fuse block with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 5 | Go to Step 9 |
| 5 | 1. Turn the ignition OFF. 2. Disconnect the engine control module (ECM) electrical connector. 3. Turn the ignition ON, with the engine OFF. 4. Probe the main relay control circuit terminal at the engine fuse block with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 6 | Go to Step 12 |
| 6 | 1. Turn the ignition OFF. 2. Disconnect the negative battery cable at the battery. 3. Disconnect the engine fuse block electrical connector. 4. Disconnect the main relay control circuit wire terminal from the engine fuse block electrical connector. 5. Connect the electrical connector that contained the main relay control circuit to the engine fuse block. 6. Connect the negative battery cable at the battery. 7. Turn the ignition ON, with the engine OFF. 8. Probe the main relay control circuit wire terminal at the ECM electrical connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 13 | Go to Step 15 |
| 7 | 1. Turn the ignition OFF. 2. Disconnect the ECM electrical connector. 3. Probe the relay coil control circuit terminal at the engine fuse block with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 8 | Go to Step 12 |
| 8 | 1. Turn the ignition OFF. 2. Disconnect the negative battery cable at the battery. 3. Disconnect the engine fuse block electrical connector. 4. Connect the negative battery cable at the battery. 5. Probe the main relay control circuit wire terminal at the engine fuse block electrical connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | - | Go to Step 13 | Go to Step 13 |
| 9 | Measure the resistance from terminal 30 of the relay to terminal 85 with a DMM. Does the DMM display the specified value? | Infinite Ohms | Go to Step 10 | Go to Step 14 |
| 10 | Measure the resistance from terminal 85 of the relay to terminal 87 with a DMM. Does the DMM display the specified value? | - | Go to Step 10 | 10 Go to Step 14 |
| 11 | Measure the resistance from terminal 85 of the relay to terminal 86 with a DMM. Does the DMM display the specified value? | 70-110 Ohms | Go to Step 17 | Go to Step 14 |
| 12 | Test for shorted terminals and poor connections at the ECM. Did you find and correct the condition? | - | Go to Step 17 | Go to Step 16 |
| 13 | Repair the short to voltage in the main relay control circuit between the engine fuse block electrical connector and the ECM electrical connector. Did you complete the repair? | - | Go to Step 17 | - |
| 14 | Replace the main relay. Did you complete the replacement? | - | Go to Step 17 | - |
| 15 | Replace the engine fuse block. Did you complete the replacement? | - | Go to Step 17 | - |
| 16 | Replace the ECM. Did you complete the replacement? | - | Go to Step 17 | - |
| 17 | 1. Reassemble the vehicle as necessary. 2. Replace any open fuses. 3. Turn the ignition OFF for 30 seconds. 4. Attempt to start the engine. Does the engine start and run? | - | Go to Step 18 | Go to Engine Cranks But Will Not Run |
| 18 | 1. Clear the DTCs with a scan tool. 2. Operate the vehicle for 5 minutes. Does the DTC set during this ignition cycle? | - | Go to applicable DTC table | System OK |