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 Descriptors

DTC C0045 00 : Rear Left Wheel Speed Sensor Malfunction
DTC C0045 5A: Rear Left Wheel Speed Sensor Plausibility Error
DTC C0050 00 : Rear Right Wheel Speed Sensor Malfunction
DTC C0050 5A: Rear Right Wheel Speed Sensor Plausibility Error

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Left Rear Sensor Signal Circuit | C0045 00 | C0045 00 | C0045 00 | C0045 5A
Left Rear Sensor Low Reference Circuit | C0045 00 | C0045 00 | C0045 00 | C0045 5A
Right Rear Sensor Signal Circuit | C0050 00 | C0050 00 | C0050 00 | C0050 5A
Right Rear Sensor Low Reference Circuit | C0050 00 | C0050 00 | C0050 00 | C0050 5A

### Circuit/System Description

The wheel speed sensor receives a 12-volt power supply voltage from the electronic brake control module (EBCM) and provides an output signal to the EBCM. As the wheel spins, the wheel speed sensor sends the EBCM a DC square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.

### Conditions for Running the DTC

#### C0045 00 - C0050 00

The ignition is ON.

#### C0045 5A - C0050 5A

• | The ignition is ON.

• | The vehicle speed is greater than 16 km/h (10 mph).

• | Ignition voltage is greater than 8 volts.

• | The brake pedal is not pressed.

• | A DTC is not set for the other wheel speed circuit on the same axle.

### Conditions for Setting the DTC

• | An erratic signal output of the wheel speed sensor is detected.

• | A short to voltage, open or ground is detected on the wheel speed sensor signal circuit.

• | A open or short to ground in the wheel speed sensor circuit supply voltage.

• | Wheel speed sensor power supply is less than 7.6 volts.

• | A missing wheel speed sensor signal.

### Action Taken When the DTC Sets

• | The EBCM disables the Antilock Brake System (ABS)/Traction Control System (TCS)/Electronic Stability Control (ESP) 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 EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

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

### Diagnostic Aids

If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.

#### C0045 5A, 00 - C0050 5A, 00

If the customer comments that the ABS indicator is ON only during moist environmental conditions: rain, snow, vehicle wash, etc., inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:

1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 2 teaspoons of salt to 8 fl oz of water (10 g of salt to 200 ml of water).
2. Test drive the vehicle over various road surfaces, bumps, turns, etc., above 50 km/h (31 mph) for at least 20 seconds.
3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
4. Rinse the area thoroughly when completed.

### 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 the scan tool installed drive the vehicle in a straight line at a speed greater than 20 km/h (13 mph), all wheel speed sensors should read the same speed.

### Circuit/System Testing

Note: It is recommend that Component Testing is performed before Circuit Testing when diagnosing wheel speed sensors.

Note: Performing Circuit Testing with EBCM connector disconnected and key on will cause U codes to set. Clear DTCs after performing the test.

1. Ignition OFF, disconnect the EBCM connector. Ignition ON, measure for 0 volts between the wheel speed sensor signal circuit or the wheel speed sensor low reference circuit and ground at the EBCM connector.

⇒ | If over 0 volt, repair short to voltage in the wheel speed sensor signal circuit or the wheel speed sensor supply voltage circuit.

2. Ignition OFF, disconnect the wheel speed sensor harness, measure for infinite ohms of resistance between ground and the wheel speed sensor signal and the wheel speed sensor low reference circuit from the EBCM connector.

⇒ | If less than infinite ohms, repair short to ground in the sensor signal or the low reference circuit.

3. Measure for infinite ohms of resistance between the wheel speed sensor signal circuit and the wheel speed low reference circuit at the EBCM connector.

⇒ | If less than infinite ohms, repair short between the wheel speed sensor signal circuit and the wheel speed sensor low reference circuit.

⇒ | If all circuits test normal replace the suspect wheel speed sensor.

### Component Testing

1. Ignition OFF, disconnect the wheel speed sensor connector. Connect a 12 volt test light from B+ to the positive side of the wheel speed sensor connect terminal, and the other wheel speed connector terminal to a DMM positive lead and the other lead to ground. The DMM is set on the mA display.

⇒ | If the reading is below 4 mA replace the wheel speed sensor.

2. At the wheel speed sensor, set-up a DMM to measure current flow (mA/A). Spin the wheel very slowly. Measure for 4-8 mA on the low reading and 12-16 mA on the high reading.

⇒ | If the low amperage output of the wheel speed sensor signal circuit is below 4 mA or above 8 mA replace the wheel speed sensor.

⇒ | If the high amperage output of the wheel speed sensor signal circuit is below 12 mA or above 16 mA replace the wheel speed sensor.

### Repair Instructions

• | Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Rear Wheel Speed Sensor Replacement

• | Control Module References