• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Left Front Sensor Supply Voltage | C0035 00 | C0035 00 | C0035 00 | C0035 0F, 18 |
Left Front Sensor Signal | C0035 00 | C0035 00 | C0035 00 | C0035 0F, 18 |
Right Front SensorSupply Voltage | C0040 00 | C0040 00 | C0040 00 | C0040 0F, 18 |
Right Front Sensor Signal | C0040 00 | C0040 00 | C0040 00 | C0040 0F, 18 |
Left Rear Sensor Supply Voltage | C0045 00 | C0045 00 | C0045 00 | C0045 0F, 18 |
Left Rear Sensor Signal | C0045 00 | C0045 00 | C0045 00 | C0045 0F, 18 |
Right Rear Sensor Supply Voltage | C0050 00 | C0050 00 | C0050 00 | C0050 0F, 18 |
Right Rear Sensor Signal | C0050 00 | C0050 00 | C0050 00 | C0050 0F, 18 |
The wheel speed sensor (WSS) receives ignition voltage from the electronic brake control module (EBCM) and provides a DC square wave signal back to the module. As the wheel spins, the EBCM uses the frequency of the square wave signal to calculate the wheel speed.
Ignition ON.
• | Ignition ON. |
• | The brake pedal is not pressed. |
• | A DTC is not set for the other wheel speed circuit on the same axle. |
• | Ignition ON. |
• | 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. |
A short to voltage, short to ground or an open/high resistance is detected on a wheel speed sensor circuit.
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 seconds between occurrences.
• | 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. |
• | The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/ vehicle stability enhancement system (VSES) for the duration of the ignition cycle. |
• | A DIC message and/or a warning indicator may be displayed. |
• | The condition for setting the DTC is no longer present. |
• | The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
• | A damaged rear wheel speed sensor ring can cause failure type byte OF (Erratic Signal) to set. |
• | If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually. |
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:
Antilock Brake System Schematics
Control Module References for scan tool information
Observe the scan tool Wheel Speed Sensor parameter. The reading should be the same speed on all sensors when driving in a straight line at a speed greater than 20 km/h (13 mph).
• | LF Sensor circuit terminal 12 |
• | RF Sensor circuit terminal 26 |
• | LR Sensor circuit terminal 42 |
• | RR Sensor circuit terminal 43 |
⇒ | If greater than the specified range, test the ignition voltage circuit for a short to voltage. |
• | LF Sensor circuit terminal 13 |
• | RF Sensor circuit terminal 27 |
• | LR Sensor circuit terminal 41 |
• | RR Sensor circuit terminal 44 |
⇒ | If greater than the specified range, test the signal circuit for a short to voltage. |
• | LF Sensor circuit terminal 12 |
• | RF Sensor circuit terminal 26 |
• | LR Sensor circuit terminal 42 |
• | RR Sensor circuit terminal 43 |
⇒ | If less than the specified value, test the ignition voltage circuit for a short to ground. |
• | LF Sensor circuit terminal 13 |
• | RF Sensor circuit terminal 27 |
• | LR Sensor circuit terminal 41 |
• | RR Sensor circuit terminal 44 |
⇒ | If less than the specified value, test the signal circuit for a short to ground. |
• | LF Sensor circuit terminal 12 at the EBCM harness connector and terminal A at the WSS harness connector. |
• | RF Sensor circuit terminal 26 at the EBCM harness connector and terminal A at the WSS harness connector. |
• | LR Sensor circuit terminal 42 at the EBCM harness connector and terminal A at the WSS harness connector. |
• | RR Sensor circuit terminal 43 at the EBCM harness connector and terminal A at the WSS harness connector. |
⇒ | If greater than the specified value, test the ignition voltage circuit for an open or high resistance. |
• | LF Sensor circuit terminal 13 at the EBCM harness connector and terminal B at the WSS harness connector. |
• | RF Sensor circuit terminal 27 at the EBCM harness connector and terminal B at the WSS harness connector. |
• | LR Sensor circuit terminal 41 at the EBCM harness connector and terminal B at the WSS harness connector. |
• | RR Sensor circuit terminal 44 at the EBCM harness connector and terminal B at the WSS harness connector. |
⇒ | If greater than the specified value, test the signal circuit for an open or high resistance. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for EBCM replacement, setup, and programming |