DTC 21
DTC 11, 12, 13, 14: Wheel Speed Sensor (Open circuit or short circuit) DTC 21, 22, 23, 24: Wheel Speed Sensor
CIRCUIT OPERATION
^ A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each wheel speed sensor.
^ The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the wheel speed sensor, and by the speed of rotation.
^ The wheel speed sensors transmit the frequency of the voltage pulses and the amount of voltage generated by each pulse to the ABS electronic control unit (ABS-ECU).
^ The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.
ABS DTC SET CONDITIONS
^ DTCs 11, 12, 13, 14 are output when signal is not input due to breakage of the (+) or (-) wire of one or more of the four wheel-speed sensors. DTCs 21, 22, 23, 24 are output in the following cases:
^ Open circuit is not found but no input is received by one or more of the four wheel-speed sensors at 10 km/h (6 mph) or more.
^ Sensor output drops due to a malfunctioning sensor or warped ABS rotor
TROUBLESHOOTING HINTS (The most likely causes for these DTCs to set are:)
DTC 11, 12, 13, 14
^ Malfunction of the wheel speed sensor
^ Damaged wiring harness or connector
^ Malfunction of the hydraulic unit (Integrated with ABS-ECU) DTC 21, 22, 23, 24
^ Malfunction of the wheel speed sensor
^ Damaged wiring harness and connector
^ Malfunction of the hydraulic unit (Integrated with ABS-ECU)
^ Malfunction of the ABS rotor
^ Malfunction of the wheel bearing
^ Excessive clearance between the sensor and ABS rotor
DIAGNOSIS
Required Special Tool:
^ MB991223: Harness Set
STEP 1. Check the wheel speed sensor installation.
Q: Is the wheel speed sensor bolted securely in place at the front knuckle or the rear knuckle?
YES: Go to Step 2.
NO: Install it properly. Then go to Step 10.
STEP 2. Check the wheel speed sensor circuit at ABS-ECU connector A-02.
1) Disconnect connector A-02 and measure at the harness side.
2) Measure the resistance between the ABS-ECU connector terminals 1 and 3, 4 and 5, 6 and 7, 8 and 9.
Standard Value: 1.28 - 1.92 k ohms
Q: Is the resistance between terminals 1 and 3, 4 and 5, 6 and 7, 8 and 9 within the standard value?
YES: Go to Step 7.
NO: Go to Step 3,4,5 or 6.
STEP 3. Check the harness wires between ABS-ECU connector A-02 terminal 6 and wheel speed sensor
NOTE: After inspecting intermediate connector C-05, inspect the wire. If intermediate connector C-05 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 10.
Q: Are any harness wires between ABS-ECU connector A02 terminal 6 and wheel speed sensor front: LH> connector A-22 terminal 1 or ABS-ECU connector A-02 terminal 7 and wheel speed sensor front: LH> connector A-22 terminal 2 damaged?
YES: Repair them and go to Step 10.
NO: Go to Step 8.
STEP 4. Check the harness wires between ABS-ECU connector A-02 terminal 4 and wheel speed sensor
Q: Are any harness wires between ABS-ECU connector A02 terminal 4 and wheel speed sensor
YES: Repair them and then go to Step 10.
NO: Go to Step 8.
STEP 5. Check the harness wires between ABS-ECU connector A-02 terminal 1 and wheel speed sensor
NOTE: After inspecting intermediate connectors C-212,C-210 and D-16, inspect the wire. If intermediate connector C-212, C210 or D-16 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 10.
Q: Are any harness wires between ABS-ECU connector A02 terminal 1 and wheel speed sensor
YES: Repair them and then go to Step 10.
NO: Go to Step 8.
STEP 6. Check the harness wires between ABS-ECU connector A-02 terminal 8 and wheel speed sensor Rear RH> connector D-10 terminal 1 or ABS-ECU connector A02 terminal 9 and wheel speed sensor Wear RHO connector D-10 terminal 2.
NOTE: After inspecting intermediate connectors C-212,C-210 and D-16, inspect the wire. If intermediate connector C-212,C210 or D-16 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 10.
Q: Are any harness wires between ABS-ECU connector A02 terminal 8 and wheel speed sensor Great RH> connector D-10 terminal 1 or ABS-ECU connector A-02 terminal 9 and wheel speed sensor Freer RH> connector D-10 terminal 2 damaged?
YES: Repair them and then go to Step 10.
NO: Go to Step 8.
STEP 7. Check the wheel speed sensor output voltage.
Output Voltage:
^ When measured with a voltmeter: 42 mV or more
^ When measured with an oscilloscope (maximum voltage): 200 mV or more
Q: Does the voltage meet the specification?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 10.
NO: Go to Step 8.
STEP 8. Check the wheel speed sensor or ABS rotor.
If there is damage in any of the check items, replace the wheel speed sensor.
Check items:
^ Wheel speed sensor internal resistance Standard value: 1.28 - 1.92 k ohms
^ Insulation between the Wheel speed sensor body and connector terminals
^ Toothed ABS rotor check
Q: Is the wheel speed sensor or ABS rotor damaged?
YES: Replace it and then go to Step 10.
NO: Go to Step 9.
STEP 9. Check the wheel bearing.
Q: Is the wheel bearing damaged?
YES: Replace it and then go to Step 10.
NO: Go to Step 10.
STEP 10. Check the diagnostic trouble code.
Q: Are diagnostic trouble codes 11, 12, 13, 14, 21, 22, 23 and 24 reset?
YES: Go to Step 1.
NO: The procedure is complete.
DTC 15: Wheel Speed Sensor (Abnormal output signal)
WHEEL SPEED SENSOR CIRCUIT
Refer to diagnostic trouble codes 11.
CIRCUIT OPERATION
Refer to diagnostic trouble codes 11.
ABS DTC SET CONDITIONS
^ DTC 15 is output when output signal produced by any of wheel-speed sensor is abnormal (excluding short and open-circuits).
TROUBLESHOOTING HINTS (The most likely causes for this DTC to set are:)
^ Improper installation of the wheel speed sensor
^ Malfunction of the wheel speed sensor
^ Damaged wiring harness or connector
^ Malfunction of the ABS rotor
^ Malfunction of the wheel bearing
DIAGNOSIS
Required Special Tool:
^ MB991223: Harness Set
STEP 1. Check the wheel speed sensor installation.
Q: Is the wheel speed sensor bolted securely in place at the front knuckle or the rear knuckle?
YES: Go to Step 2.
NO: Install it properly. Then go to Step 9.
STEP 2. Check the harness wires between ABS-ECU connector A-02 terminal 6 and wheel speed sensor front: LH> connector A-22 terminal 1 or ABS-ECU connector A02 terminal 7 and wheel speed sensor front: LH> connector A-22 terminal 2.
NOTE: After inspecting intermediate connector C-05, inspect the wires. If intermediate connector C-05 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 9.
Q: Are any harness wires between ABS-ECU connector A02 terminal 6 and wheel speed sensor front: LH> connector A-22 terminal 1 or ABS-ECU connector A-02 terminal 7 and wheel speed sensor front: LH> connector A-22 terminal 2 damaged?
YES: Repair them and go to Step 9.
NO: Go to Step 7.
STEP 3. Check the harness wires between ABS-ECU connector A-02 terminal 4 and wheel speed sensor
Q: Are any harness wires between ABS-ECU connector A02 terminal 4 and wheel speed sensor
YES: Repair them and then go to Step 9.
NO: Go to Step 7.
STEP 4. Check the harness wires between ABS-ECU connector A-02 terminal 1 and wheel speed sensor
NOTE: After inspecting intermediate connectors C-212, C-210 and D-16, inspect the wire. If intermediate connector C-212, C210 or D-16 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 9.
Q: Are any harness wires between ABS-ECU connector A02 terminal 1 and wheel speed sensor
YES: Repair them and then go to Step 9.
NO: Go to Step 7.
STEP 5. Check the harness wires between ABS-ECU connector A-02 terminal 8 and wheel speed sensor
NOTE: After inspecting intermediate connectors C-212, C-210 and D-16, inspect the wire. If intermediate connector C-212, C210 or D-16 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 9.
Q: Are any harness wires between ABS-ECU connector A02 terminal 8 and wheel speed sensor Wear RH> connector D-10 terminal 1 or ABS-ECU connector A-02 terminal 9 and wheel speed sensor Rear RH> connector D-10 terminal 2 damaged?
YES: Repair them and then go to Step 9.
NO: Go to Step 7.
STEP 6. Check the wheel speed sensor output voltage.
Output Voltage:
^ When measured with a voltmeter: 42 mV or more
^ When measured with an oscilloscope (maximum voltage): 200 mV or more
Q: Does the voltage meet the specification?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 9.
NO: Go to Step 7.
STEP 7. Check the wheel speed sensor or ABS rotor. If there is damage in any of the check items, replace the wheel speed sensor.
Check items:
^ Wheel speed sensor internal resistance
Standard value: 1.28 - 1.92 k ohms
^ Insulation between the wheel speed sensor body and the connector terminals
^ Toothed ABS rotor check
Q: Is the wheel speed sensor or ABS rotor damaged?
YES: Replace it and then go to Step 9.
NO: Go to Step 8.
STEP 8. Check the wheel bearing.
Q: Is the wheel bearing damaged?
YES: Replace it and then go to Step 9.
NO: Go to Step 9.
STEP 9. Check the diagnostic trouble code.
Q: Do the diagnostic trouble code 15 reset?
YES: Go to Step 1.
NO: The procedure is complete.