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 C0900 00: Power Supply Circuit High Voltage

### Circuit Description

The electronic brake control module (EBCM) monitors the voltage level available for system operation. If the voltage level is too high, damage may result in the system. When the EBCM detects a high voltage condition, the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.

### Conditions for Running the DTC

• | The ignition is ON.

• | The vehicle speed is greater than 8 km/h (5 mph).

### Conditions for Setting the DTC

One of the following conditions exists for 0.72 seconds:

• | During initialization or when the system is inactive, the system voltage is greater than 16.8 volts.

• | During the system operation, the system voltage is greater than 16.7 volts.

### Action Taken When the DTC Sets

• | The EBCM disables the Antilock Brake System (ABS)/Traction Control System (TCS)/Electronic Stability Control (ESP)/Electronic Brake Distribution (EBD) for the duration of the ignition cycle.

• | The multi function display (MFD) displays the ABS Fault message.

• | The multi function display (MFD) displays the Traction Ctrl Off message.

• | The multi function display (MFD) displays the Stability Ctrl Off message.

### Conditions for Clearing the DTC

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

• | The DTC can be cleared using a scan tool.

### Diagnostic Aids

• | Test the charging system. Refer to Charging System Test .

• | Possible causes of this DTC are the following conditions:

| A charging system malfunction

### Reference Information

#### Schematic Reference

Antilock Brake System Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

With scan tool installed, clear the DTCs then drive the vehicle in a straight line at a speed greater than 20 km/h (13 mph).

### Circuit/System Testing

1. Start the engine and allow to idle, using a scan tool check if DTC is set to current.

⇒ | If the DTC is set to current, continue.

2. Ignition OFF, disconnect the EBCM harness connector.
3. Test for less than 1.0 ohm of resistance between the ground circuit terminals and ground.

⇒ | If greater than the specified range, test the ground circuits for an open/high resistance.

4. Connect a DMM between the supply voltage circuit terminals and the ground circuit terminals.

⇒ | If 12 volts is present, replace the EBCM.

⇒ | If greater than 116 volts is present, test and repair charging system.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Electronic Brake Control Module Replacement .

• | Control Module References .