C0712
DTC C0712
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC C0712
- Vehicle Level Control Compressor Relay Circuit
For symptom byte information, refer to Symptom Byte List Symptom Byte List
Diagnostic Fault Information
Circuit/System Description
The Suspension Control Module adjusts the vehicle suspension ride height. The Suspension Control Module determines the height of the vehicle based on the voltage from the suspension position sensors. The module supplies B+ to the Vehicle Level Control Compressor relay to raise and lower the vehicle in order to keep the vehicle level.
Conditions for Running the DTC
* The Suspension Control Module is powered up.
* The Suspension Control Module is commanding the compressor ON.
Conditions for Setting the DTC
* The compressor relay coil control circuit is shorted to voltage, ground, or open for 5 seconds.
* The compressor relay coil supply voltage circuit is shorted to ground, or open for 5 seconds.
Action Taken When the DTC Sets
The automatic level control system will be inoperative.
Conditions for Clearing the DTC
The Suspension Control Module does not detect a failure during the self test.
Diagnostic Aids
This circuit is monitored during every functional operation of the compressor relay output and every 3.3 milliseconds when output is active. If a compressor relay fault is detected, the Suspension Control Module retries the output every 15 seconds to try to recover from the fault.
Reference Information
Schematic Reference
Electronic Suspension Control Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Electronic Suspension Control Description and Operation Electronic Suspension Control
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, engine running.
2. Listen for the operation of the Vehicle Level Control Compressor relay and the automatic level control compressor.
• If the Vehicle Level Control Compressor relay and the automatic level control compressor cannot be heard
1. Refer to Circuit/System Testing
• If the Vehicle Level Control Compressor relay and the automatic level control compressor are heard
3. All OK
Circuit/System Testing
1. Ignition OFF, all vehicle systems OFF. Disconnect the KR96 Vehicle Level Control Compressor Relay It may take up to 2 min for all vehicle systems to power down.
2. Ignition ON, verify a test lamp illuminates between the KR96 Vehicle Level Control Compressor Relay terminal 30 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp foes not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Disconnect the harness connector at the G3 Air Suspension Compressor.
4. Test for infinite resistance between the control circuit terminal 87 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the G3 Air Suspension Compressor.
• If the test lamp illuminates
3. Momentarily install a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
4. Verify the G3 Air Suspension Compressor is activated.
• If the G3 Air Suspension Compressor does not activate
1. Disconnect the harness connector at the G3 Air Suspension Compressor.
2. Test for less than 2 ohms in the control circuit end to end.
• If greater than 2 ohms, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the G3 Air Suspension Compressor.
• If the G3 Air Suspension Compressor activates
5. Replace the KR96 Vehicle Level Control Compressor Relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the KR96 Vehicle Level Control Compressor Relay.
2. Test for 60-180 ohms between terminals 85 and 86.
• If less than 60 or greater than 180 ohms
Replace the KR96 Vehicle Level Control Compressor Relay.
• If between 60-180 ohms
3. Test for infinite resistance between the terminals listed below:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If less than infinite resistance
Replace the KR96 Vehicle Level Control Compressor Relay.
• If infinite resistance
4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
5. Test for less than 2 ohms between terminals 30 and 87A.
• If 2 ohms or greater
Replace the KR96 Vehicle Level Control Compressor Relay.
• If less than 2 ohms
6. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Rear Air Spring Compressor Replacement Rear Air Spring Compressor Replacement
* Electronic Suspension Rear Position Sensor Trim Height Calibration Electronic Suspension Rear Position Sensor Trim Height Calibration
* Control Module References Control Module References for Suspension Control Module replacement, programming, and setup.