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 Open or Shorted Signal

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 Open or Shorted Signal

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 Open or Shorted Signal

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 Open or Shorted Signal

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 two other wheel speeds are not 0 km/h.

Conditions for Setting the DTC

C0035 00-C0050 00 Open or Shorted Signal

    • 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 Erratic Signal or Sensor Dropout

Sensor Dropout

Detects a missing sensor signal when the vehicle has been in motion with all sensors working.

    • All wheel speeds have been read as greater than 12.9 km/h (8 mph).
    • One wheel speed suddenly reads 0 km/h (0 mph) within 15 msec.
    • Vehicle velocity remains greater than 12.9 km/h (8 mph).

OR

Erratic Signal

    • Any wheel speed changes by 17.7 km/h (11 mph) or more in 0.01 second.
    • Vehicle velocity remains greater than 12.9 km/h (8 mph).

C0035 18-C0050 18 Missing Sensor

Detects a missing sensor signal (or signals) when the vehicle accelerates from a standstill.

    • One wheel speed is less than 20 percent of the maximum of the others for 5 seconds.
    • At least one of the remaining wheel speeds are greater than 12.9 km/h (8 mph).
    • There has been no wheel acceleration/deceleration exceeding 21.9 mph/sec.

OR

    • The 2 wheel speed sensor inputs are less than 20 percent of the maximum of the others for 120 seconds.
    • At least one of the remaining wheel speeds are greater than 12.9 km/h (8 mph).
    • There has been no wheel acceleration/deceleration exceeding 21.9 mph/sec.

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

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

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

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: 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 terminal 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 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. Ignition OFF, disconnect the harness connector at the appropriate wheel speed sensor.
  2. Test for 850-1350 ohms between the signal terminal A and the low reference signal terminal B. During the test, check for an intermittent circuit condition by gentle moving the wheel speed sensor pigtail harness.
  3. If not within the specified range, replace the wheel speed sensor.
  4. Test for infinite resistance between each terminal and the steering knuckle. Reverse the test leads, test for infinite resistance between each terminal and the steering knuckle again.
  5. If less than the specified value, replace the appropriate wheel speed sensor.
  6. Spin the wheel while monitoring the voltage between the signal terminal A and the low reference terminal B. The voltage should be greater than 100 mV AC.
  7. If less than the specified range, 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