Diagnostic Instructions
DTC Descriptors
DTC C0660 01: Level Control Exhaust Circuit Short to Battery
DTC C0660 06: Level Control Exhaust Circuit Short to Ground or Open Circuit
Circuit Description
The electronic suspension control module (ESCM) adjusts the vehicle suspension ride height. The ESCM determines the height of the vehicle based on signals from the height sensors. The ESCM raises and lowers the vehicle in order to keep the vehicle level
by controlling the exhaust valve and air compressor control circuits.
Conditions for Running the DTC
| • | Battery voltage is between 9-16 volts. |
| • | The exhaust valve is commanded ON. |
Conditions for Setting the DTC
| • | The exhaust valve control circuit is shorted to voltage, ground, or open when solenoid activation is commanded ON for 2.5 seconds. |
| • | The exhaust valve supply voltage circuit is shorted to ground or open when solenoid activation is commanded ON for 5 seconds. |
Action Taken When the DTC Sets
| • | The electronic suspension control system will be inoperative. |
| • | The SERVICE SUSPENSION SYSTEM message will be displayed. |
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 50 ignition cycles. |
Reference Information
Schematic Reference
Automatic Level Control Schematics
Connector End View Reference
Description and Operation
Automatic Level Control Description and Operation
Electrical Information Reference
Scan Tool Reference
Diagnostic Aids
| • | Inspect for the addition of aftermarket components. |
| • | Inspect all wiring harnesses carefully for chaffs and proper routing. |
Circuit/System Verification
Ignition ON, command the Exhaust Valve ON and OFF with the scan tool output control. The exhaust solenoid valve should turn ON and OFF with each command.
Circuit/System Testing
- Ignition OFF, disconnect the automatic level control (ALC) compressor exhaust solenoid.
- Ignition ON, verify that a test lamp does not illuminate between the solenoid control circuit terminal A at the connector 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+ circuits for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the ALC compressor. |
- 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 ESCM. |
| ⇒ | 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 ESCM. |
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. This would include the
Suspension Position Calibration procedure.
- Clear the DTCs.
- 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.
