TCS
C1206Component Location:
General Description
The wheel speed sensor is the essential component the ABS ECU uses to calculate vehicle speed and to determine whether wheel lock occurs.
For example, rear wheel speed signal is used as a reference value, for vehicle speed, in front wheel drive vehicles, and if a difference between front and rear wheel speed occurs, then ABS control is performed.
Wheel speed sensor is active hall-sensor type.
DTC Description
The ABS ECU monitors the wheel speed sensor circuit continuously. Each wheel speed sensor is checked separately.
A failure is detected if the measured sensor signal current is continuously out of the specified range for the specified min. fault duration.
Warning lamp is turned OFF unless additional faults are detected when the IG KEY is turned ON again, and wheel speed is more than 10 km/h. (6.2 mph)
DTC Detecting Condition:
Specification:
Schematic Diagram:
Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC)
2. Engine "ON".
3. Start and drive vehicle in gear and maintain vehicle speed at or above 10 km/h. (6.2 mph)
4. Monitor the "WHEEL SPD SNSOR-RL" parameter on the Scantool.
Specification : Compare with other parameters related to wheel speed sensor. If it is the same as other parameters, it is in normal condition.
5. Is parameter displayed within specifications?
YES - Fault is intermittent caused by poor connection in wheel speed sensor harness (RL) and/or HECU's connector or was repaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "W/Harness Inspection" procedure.
Terminal and Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness (es) and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "Power Circuit Inspection" procedure.
Power Supply Circuit Inspection
1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminal "2" of the wheel speed sensor (RL) harness connector and chassis ground.
Specification : Approx. B+
3. Is the measured voltage within specifications?
YES - Go to "Signal Circuit Inspection" procedure.
NO
- Check for open or short to GND in wheel speed sensor harness (RL) between terminal "2" of the wheel speed sensor (RL) harness connector and terminal "36" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
- If OK, Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.
Signal Circuit Inspection
1. Ignition "OFF".
2. Disconnect wheel speed sensor (RL) and HECU connector.
3. Measure resistance between terminal "37" of the HECU harness connector and terminal "1" of the wheel speed sensor (RL) harness connector.
Specification : Approx. 0 ohms
4. Is the measured resistance within specifications?
YES
- Check for short wheel speed sensor harness (RL-) between terminal "1" of the wheel speed sensor (RL) harness connector and terminal "37" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure. If OK, go to "Component Inspection" procedure.
- If OK, go to "Component Inspection" procedure.
NO - Check for open wheel speed sensor harness (RL-) between terminal "1" of the wheel speed sensor (RL) harness connector and terminal "37" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Component Inspection
1. Ignition "OFF".
2. Disconnect the wheel speed sensor harness connector.
3. Connect resistance (approx. 100 ohms) to the wheel speed sensor signal circuit.
4. Measure waveform of the wheel speed sensor signal harness while turning the wheel.
Specification : High : Approx. 1.4 V, Low : Approx. 0.7 V (In case that 100 ohms resistance is used)
NOTE: Voltage of the waveform can be calculated by using following expression.
Voltage = Resistance • Current (High : 1.4 mA, Low : 0.7 mA)
5. Is the measured waveform within specifications?
YES - Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of vehicle Repair" procedure.
NO
- Check for improper installation of wheel speed sensor. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
- Check for damage of rotor teeth or wheel bearing. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
- Substitute with a known-good Wheel speed sensor and check for proper operation. If problem is corrected, replace Wheel speed sensor and then go to "Verification of Vehicle Repair" procedure.
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Using a Scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information. (Start and drive vehicle in gear and maintain vehicle speed at or above 10 km/h. (6.2 mph))
4. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System performing to specification at this time.