For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC C0394 06: Rear Axle Coupling Temperature Sensor Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
High Coupling Temperature Sensor Circuit | C0394 06 | C0394 06 | -- | --
Low Coupling Temperature Sensor Circuit | -- | C0394 06 | -- | --

### Circuit/System Description

The coupling control module (CCM) provides a power and ground circuits to the coupling temperature sensor. When the temperature of the module is determined to be beyond its limits, the CCM will temporarily disable the rear drive system.

### Conditions for Running the DTC

• | The ignition is ON.

• | Ignition voltage is greater than 9 volts.

### Conditions for Setting the DTC

• | An open is detected on the high or low temperature sensor circuits.

• | A short to ground is detected on the high temperature sensor circuit.

• | An open in the low temperature sensor circuit.

### Action Taken When the DTC Sets

One or more of the following actions may occur:

• | All Wheel Drive Off (AWD Disabled).

• | Service All Wheel Drive (Service AWD).

### Conditions for Clearing the DTC

• | The condition for the DTC is no longer present.

• | The DTC is not detected in 100 consecutive drive cycles.

### Reference Information

#### Schematic Reference

Rear Axle Schematics

Differential Lock Schematics

#### Connector End View Reference

Rear Axle Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Verification

DTC C0394 will set as result of CCM temperature sensor or circuit failure, test for power and ground circuits to the CCM.

⇒ | Repair the power or ground circuits.

### Circuit/System Testing

Important: It is recommend that Component Testing is performed before Circuit Testing when diagnosing the power vacuum booster Solenoid.

1. Ignition OFF, disconnect the 5 way harness connector at the CCM.
2. Test for less than 1 ohm between the ground circuit terminal and ground.

⇒ | If greater than 1 ohm, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the Battery circuit terminal and the ground circuit terminal.
4. Ignition On engine Off. The test lamp should turn ON.

⇒ | If the test lamp is always ON, test the CCM circuits for an open or short to ground. If the circuit tests normal, replace the coupling control module (CCM).

⇒ | If the test lamp is always OFF, test the Battery circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the coupling solenoid.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for CCM replacement, setup, and programming

• | Power Vacuum Brake Booster Replacement