P0688

P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW

Special Tools:










For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation
For information for ASD relay description and operation Auto Shutdown Relay - Description.For specific relay location and type, Locations.
- When Monitored:
With ignition key on. Battery voltage greater than 10 Volts.

- Set Condition:
No voltage sensed at the PCM when the ASD relay is energized. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. VERIFY ASD DTC

NOTE: If any O2 SENSOR HEATER CIRCUIT HIGH DTCs set along with P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW, all of the O2 Sensor Heater Control circuits need to be checked for a short to battery voltage.

NOTE: If any of the following component DTCs have set along with P0688, diagnose them first before continuing.Ignition Coil(s)Fuel Injector(s)ASD ControlASD Control Output (TIPM DTC)

1. With the scan tool, erase the DTC.
2. 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 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. ENGINE OPERATION
1. Attempt to start the engine.

Does the engine start?

Yes

- Go To 3

No

- Go To 4

3. (F342) ASD RELAY OUTPUT CIRCUIT OPEN




1. Turn the ignition off.
2. Remove the ASD Relay. Auto Shutdown Relay - Removal.
3. Disconnect the C1and 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 the PCM Pinout Box (8815A) to perform diagnosis.

4. Measure the resistance of the (F342) ASD Relay Output circuit from the Relay connection to the appropriate terminals of PCM Pinout Box.

Is the resistance below 5.0 Ohms?

Yes

- Go To 7

No

- Repair the open in the (F342) ASD Relay Output circuits.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. ASD RELAY
1. Turn the ignition off.
2. Install a substitute relay in place of the ASD Relay. Auto Shutdown Relay - Removal.
3. Ignition on, engine not running.
4. With the scan tool, erase DTCs.
5. Attempt to start the engine.
6. With the scan tool, select View DTCs.

Does the DTC reset?

Yes

- Go To 5

No

- Replace the ASD Relay. Auto Shutdown Relay - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (A209) FUSED B+ CIRCUITS




1. Turn the ignition off.
2. Using a 12-volt test light connected to ground, probe the (A209) Fused B+ circuits at the Relay connection.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 6

No

- Repair the open or short to ground in the (A209) Fused B+ circuits. Inspect the related fuse and repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. (F342) ASD RELAY OUTPUT CIRCUIT OPEN




1. Disconnect the C1 and 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 the PCM Pinout Box (8815A) to perform diagnosis.

2. Measure the resistance of the (F342) ASD Relay Output circuit from the Relay connection to the appropriate terminals of PCM Pinout Box.

Is the resistance below 5.0 Ohms?

Yes

- Go To 7

No

- Repair the open in the (F342) ASD Relay Output circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ASD Relay and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ASD Relay and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.