P0688
P0688 - ASD/Main Sense Circuit
For wiring diagrams, refer to.
• When Monitored: With the control circuit active and battery voltage greater than 10.4 volts.
• Set Condition: The PCM detects that the ASD relay output circuit voltage is not within the specified range based on operation conditions.
• Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - DTC is Active
• Turn the ignition ON.
• With the scan tool, Clear DTCs in the PCM.
• With the scan tool, actuate the auto shutdown relay control state.
• With the scan tool, select view DTCs.
Is the status active for this DTC?
Yes
• Go to Test Step 2 => [ Test
Step 2 - Fused B+ Circuit Open or High Resistance ]
No
• Refer to the checking for an intermittent DTC diagnostic procedure. Refer to => Non-DTC Based Diagnostics. Checking for an Intermittent DTC
Test Step 2 - Fused B+ Circuit Open or High Resistance
• Turn the ignition OFF.
• Remove the auto shutdown relay.
• Turn the ignition ON.
• Using a test lamp connected to ground, check both fused B+ circuits in the auto shutdown relay connector.
• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test lamp illuminated and bright?
Yes
• Go to Test Step 3 => [ Test
Step 3 - ASD Relay Output Circuit Shorted to Voltage ]
No
• Repair the fused B+ circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 3 - ASD Relay Output Circuit Shorted to Voltage
• Turn the ignition OFF.
• Disconnect the PCM connectors.
• Turn the ignition ON.
• Measure the voltage of each of the ASD relay output circuits in the auto shutdown relay connector.
Is there any voltage present?
Yes
• Repair the ASD relay output circuit for a short to voltage.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 4 => [ Test
Step 4 - ASD Relay Output Circuit Shorted to Ground ]
Test Step 4 - ASD Relay Output Circuit Shorted to Ground
• Turn the ignition OFF.
• Measure the resistance between ground and the ASD relay output circuit in the auto shutdown relay connector.
Is the resistance less than 100 ohms?
Yes
• Repair the ASD relay output circuit for a short to ground.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 5 => [ Test
Step 5 - ASD Relay Output Circuit Open or High Resistance ]
Test Step 5 - ASD Relay Output Circuit Open or High Resistance
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 ASD relay output circuits between the auto shutdown relay connector and each of the appropriate terminals of special tool #8815.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 6 => [ Test
Step 6 - Auto Shutdown Relay ]
No
• Repair the ASD relay output circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 6 - Auto Shutdown Relay
• Turn the ignition OFF.
• Install the auto shutdown relay.
• Connect the PCM connectors.
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 along with the #8815-1 to perform the diagnosis.
• Turn the ignition ON.
• With the scan tool, actuate the auto shutdown relay control state.
• Measure the voltage of each of the ASD relay output circuits in the appropriate terminals of special tool #8815-1.
• If the DTC is active, the actuation test may not be allowed by the PCM. If may be necessary to clear the DTCs before starting the actuation.
• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test lamp illuminated and bright for each of the circuits during the actuation?
Yes
• Go to Test Step 7 => [ Test
Step 7 - PCM ]
No
• Replace the auto shutdown relay.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 7 - PCM
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the auto shutdown relay and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any technical service bulletins that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Replace and program the PCM.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test