GM Service Manual Online
For 1990-2009 cars only

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 C0035 00: Left Front Wheel Speed Sensor Circuit No Additional Information

DTC C0035 0F: Left Front Wheel Speed Sensor Circuit Erratic Signal

DTC C0035 18: Left Front Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum

DTC C0040 00: Right Front Wheel Speed Sensor Circuit No Additional Information

DTC C0040 0F: Right Front Wheel Speed Sensor Circuit Erratic Signal

DTC C0040 18: Right Front Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum

DTC C0045 00: Left Rear Wheel Speed Sensor Circuit No Additional Information

DTC C0045 0F: Left Rear Wheel Speed Sensor Circuit Erratic Signal

DTC C0045 18: Left Rear Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum

DTC C0050 00: Right Rear Wheel Speed Sensor Circuit No Additional Information

DTC C0050 0F: Right Rear Wheel Speed Sensor Circuit Erratic Signal

DTC C0050 18: Right Rear Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum

Diagnostic Fault Information

Circuit

Short to Ground

Open or High Resistance

Short to Voltage

Signal Performance

Left Front Sensor Signal

C0035 00

C0035 00

C0035 00

C0035 0F

C0035 18

Left Front Sensor Low Reference

C0035 00

C0035 00

C0035 00

C0035 0F

C0035 18

Right Front Sensor Signal

C0040 00

C0040 00

C0040 00

C0040 0F

C0040 18

Right Front Sensor Low Reference

C0040 00

C0040 00

C0040 00

C0040 0F

C0040 18

Left Rear Sensor Signal

C0045 00

C0045 00

C0045 00

C0045 0F¹

C0045 18

Left Rear Sensor Low Reference

C0045 00

C0045 00

C0045 00

C0045 0F¹

C0045 18

Right Rear Sensor Signal

C0050 00

C0050 00

C0050 00

C0050 0F¹

C0050 18

Right Rear Sensor Low Reference

C0050 00

C0050 00

C0050 00

C0050 0F¹

C0050 18

¹Damaged rear wheel speed sensor ring can cause code to set.

Circuit/System Description

As the wheel spins, the wheel speed sensor produces an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC

C0035 00-C0050 00

    • The ignition is ON.
    • Ignition voltage is greater than 8 volts.

C0035 0F-C0050 0F

    • The ignition is ON.
    • 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.

C0035 18-C0050 18

    • The ignition is ON.
    • Ignition voltage is greater than 8 volts.
    • The brake pedal is not pressed.
    • No other wheel speed circuit DTCs are set.
    • At least 2 other wheel speeds are not 0 km/h.

Conditions for Setting the DTC

C0035 00-C0050 00

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

C0035 0F-C0050 0F

The EBCM detects a rapid variation in the wheel speed. The wheel speed changes by 20 km/h (12 mph) or more in 0.01 second. The change must occur 3 times with no more than 0.2 second between occurrences.

C0035 18-C0050 18

    • One wheel speed is 0 km/h.
    • The remaining wheel speeds are greater than 8 km/h (5 mph).
    • The difference between the remaining wheel speeds is less than 11 km/h (7 mph) from each other.

OR

    • The 2 wheel speed sensor inputs are 0 and DTCs are set.
    • The 2 suspect wheel speeds equal zero for 6 seconds.
    • The other wheel speeds are greater than 16 km/h (10 mph).
    • The other wheel speeds are within 11 km/h (7 mph) of each other.

Action Taken When the DTC Sets

    • The EBCM disables the Antilock Brake System (ABS)/Traction Control System (TCS)/Vehicle Stability Enhancement System (VSES) for the duration of the ignition cycle.
    • The dynamic rear proportion (DRP) does not function optimally.
    • The ABS indicator turns ON.
    • The traction control indicator turns ON.
    • The driver information center (DIC) displays the Service Stability System message.

Conditions for Clearing the MIL/DTC

    • The condition for setting the DTC is no longer present and the DTC is cleared with a scan tool.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

    • A damaged rear wheel speed sensor ring can cause failure type byte 04 (Erratic Signal) to set.
    • If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.

C0035 18, 0F, 00-C0050 18, 0F, 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 40 km/h (25 mph) for at least 30 seconds.
  3. Rinse the area thoroughly when completed.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Antilock Brake System Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Scan Tool Reference

Scan Tool Data List for EBCM

Circuit/System Verification

With scan tool installed drive the vehicle in a straight line at a speed greater than 8 km/h (5 mph), all wheel speed sensors should read the same miles per hour.

Circuit/System Testing

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

  1. With the ignition OFF, disconnect the EBCM connector.
  2. With the ignition ON, measure for 0 volt between the sensor signal circuit or the low reference circuit and ground at the EBCM connector.
  3. If over 0 volt, repair short to voltage in sensor signal circuit or the low reference circuit.
  4. With the ignition OFF, Measure for infinite ohms of resistance between the wheel speed sensor signal or the low reference circuit and ground at the EBCM connector.
  5. If less than infinite ohms, repair short to ground in the sensor signal or the low reference circuit.
  6. Measure for 850-1350 ohms of resistance between the wheel speed sensor signal and low reference circuits at the EBCM connector.
  7. If greater than 1350 ohms test for an open/high resistance in the circuit or faulty wheel speed sensor.
    If less than 850 ohms test for a short between the circuits or faulty wheel speed sensor.
  8. If all circuits test normal replace the EBCM.

Component Testing

  1. Disconnect the wheel speed sensor connector.
  2. With the ignition OFF, measure for 850-1350 ohms of resistance across the wheel speed sensor.
  3. If the resistance is not between 850-1350 ohms replace the faulty wheel speed sensor.
  4. Spin the wheel, measure across the wheel speed sensor for 100 mv AC or greater.
  5. If the AC voltage is less than 100 mv replace the wheel speed sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Wheel Bearing and Hub Replacement
    •  Rear Wheel Bearing and Hub Replacement
    •  Control Module References for EBCM replacement, setup, and programming