Diagnostic Instructions
DTC Descriptors
DTC C0660 01: Level Control Exhaust Circuit shorted to voltage
DTC C0660 06: Level Control Exhaust Circuit shorted to ground or open
Circuit Description
The automatic level control (ALC) adjusts the vehicle suspension ride height. The electronic suspension control (ESC) module determines the height of the vehicle based on the signal from the rear height sensors. The ESC raises and lowers the vehicle in
order to keep the vehicle level.
Conditions for Running the DTC
| • | The ESC module is powered up. |
| • | The exhaust valve is commanded ON. |
Conditions for Setting the DTC
The exhaust valve control circuit is shorted to voltage, ground, or open.
Action Taken When the DTC Sets
The ALC will be inoperative.
Conditions for Clearing the MIL/DTC
| • | DTC C0660 will change from a current DTC to a history DTC on the next ignition cycle. |
| • | DTC C0660 will be cleared from history after 100 ignition cycles. |
Diagnostic Aids
| • | Inspect for the addition of aftermarket components. |
| • | Inspect all wiring harnesses carefully for chaffs and proper routing. |
| • | This circuit is monitored every 3 milliseconds. If the exhaust valve solenoid is found to shorted to battery for 10 milliseconds the code will be stored as current. |
Circuit/System Verification
Ignition ON, command the Automatic Level Control (ALC) exhaust solenoid valve ON and OFF with a scan tool. The exhaust solenoid valve should turn ON and OFF with each command.
Circuit/System Testing
- Ignition OFF, disconnect the automatic level control (ALC) compressor.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A and ground.
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
- Verify that a test lamp illuminates between the B+ circuit terminal C and ground.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ELC MDL fuse is open, test the control circuit for a short to ground. If the circuit
tests normal, test or replace the automatic level control (ALC) compressor assembly. |
- Connect a test lamp between the B+ circuit terminal C and the control circuit terminal A.
- Command the exhaust solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESC module. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage
or an open/high resistance. If the circuit tests normal, replace the ESC module. |
Repair Instructions
Repair Verification
- Install any components or connectors that have been removed or replaced during diagnosis.
- Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
- Clear the DTCs.
- Use the scan tool Diagnostic Counter Reset output control function to bypass the 3 consecutive ignition cycle requirement for setting a DTC. This will ensure that if a DTC was to be reset during the repair verification process, it will be displayed
on the scan tool.
- Turn OFF the ignition for 60 seconds.
- Turn ON the ignition.
- If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the
Diagnostic Trouble Code (DTC) List - Vehicle
and perform the appropriate diagnostic procedure.
