Code No. C1200 Abnormality in FR wheel speed sensor circuit
Code No. C1205 Abnormality in FL wheel speed sensor circuit
Code No. C1210 Abnormality in RR wheel speed sensor circuit
Code No. C1215 Abnormality in RL wheel speed sensor circuit










caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).

OPERATION

  • The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
  • The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

DIAGNOSIS CODE SET CONDITIONS
ASC-ECU monitors the voltage fluctuation in each wheel speed sensor circuit. If ASC-ECU detects the open or short circuit in the circuit, it will set a diagnosis code.

PROBABLE CAUSES
Current trouble
  • Damaged wiring harness and connectors
  • Noise interference
  • Malfunction of wheel speed sensor
  • ASC-ECU malfunction
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines

Q. Is the diagnosis code No.C1200, C1205, C1210, C1215 set?
Go to Step 3.
The procedure is complete.

STEP 3. M.U.T.-III data list
Check the following data list (Refer to ).

  • Item No.01: FL wheel speed sensor <Code No. C1205>
  • Item No.02: FR wheel speed sensor <Code No. C1200>
  • Item No.04: RL wheel speed sensor <Code No. C1215>
  • Item No.05: RR wheel speed sensor <Code No. C1210>

Q. Is the check result normal?
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 4.

STEP 4. Voltage measurement at the A-14 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ABS check harness (MB992335) to the harness-side connector, and then measure the voltage at the special tool connector side.
note Do not connect the special tool ABS check harness (MB992335) to ASC-ECU.
(2)Turn the electric motor switch to the "ON" position.
(3)Measure the voltage between the front wheel speed sensor power supply terminal and the body earth, and between the front wheel speed sensor signal terminal and the body earth.
Diagnosis code No.
 Check terminal
Power supply terminal
 Signal terminal
C1200
 No. 18
 No. 6
C1205
 No. 34
 No. 22
C1210
 No. 19
 No. 31
C1215
 No. 33
 No. 20
OK: 1 volt or less

Q. Is the check result normal?

Go to Step 5.

NO (Not normal at the terminal No. 18 or 6) : Go to Step 6.

NO (Not normal at the terminal No. 34 or 22) : Go to Step 8.

NO (Not normal at the terminal No. 19 or 31) : Go to Step 10.

NO (Not normal at the terminal No. 33 or 20) : Go to Step 12.

STEP 5. Resistance measurement at A-14 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ABS check harness (MB992335) to the harness-side connector, and then measure the resistance at the special tool connector side.
note Do not connect the special tool ABS check harness (MB992335) to ASC-ECU.
(2)Measure the resistance between the front wheel speed sensor power supply terminal and the body earth, and between the front wheel speed sensor signal terminal and the body earth.
Diagnosis code No.
 Check terminal
Power supply terminal
 Signal terminal
C1200
 No. 18
 No. 6
C1205
 No. 34
 No. 22
C1210
 No. 19
 No. 31
C1215
 No. 33
 No. 20
OK: No continuity

Q. Is the check result normal?

Go to Step 14.

NO (Not normal at the terminal No. 18 or 6) : Go to Step 6.

NO (Not normal at the terminal No. 34 or 22) : Go to Step 8.

NO (Not normal at the terminal No. 19 or 31) : Go to Step 10.

NO (Not normal at the terminal No. 33 or 20) : Go to Step 12.

STEP 6. Connector check: A-14 ASC-ECU connector, A-21 front wheel speed sensor <RH> connector

Q. Is the check result normal?
Go to Step 7.
Repair the defective connector.

STEP 7. Wiring harness check between A-14 ASC-ECU connector terminal No.18 and A-21 front wheel speed sensor <RH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.6 and A-21 front wheel speed sensor <RH> connector terminal No.1.
Check for short circuit in front wheel speed sensor <RH> circuit

Q. Is the check result normal?
Replace the wheel speed sensor <FR> (Refer to ).
Repair the wiring harness.

STEP 8. Connector check: A-14 ASC-ECU connector, A-18 front wheel speed sensor <LH> connector

Q. Is the check result normal?
Go to Step 9.
Repair the defective connector.

STEP 9. Wiring harness check between A-14 ASC-ECU connector terminal No.34 and A-18 front wheel speed sensor <LH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.22 and A-18 front wheel speed sensor <LH> connector terminal No.1.
Check for short circuit in front wheel speed sensor <LH> circuit

Q. Is the check result normal?
Replace the wheel speed sensor <FL> (Refer to ).
Repair the wiring harness.

STEP 10. Connector check: A-14 ASC-ECU connector, B-27 intermediate connector, C-27 rear wheel speed sensor <RH> connector

Q. Is the check result normal?
Go to Step 11.
Repair the defective connector.

STEP 11. Wiring harness check between A-14 ASC-ECU connector terminal No.19 and C-27 rear wheel speed sensor <RH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.31 and C-27 rear wheel speed sensor <RH> connector terminal No.1.
Check for short circuit in rear wheel speed sensor <RH> circuit

Q. Is the check result normal?
Replace the wheel speed sensor <RR> (Refer to ).
Repair the wiring harness.

STEP 12. Connector check: A-14 ASC-ECU connector, A-107 intermediate connector, C-15 rear wheel speed sensor <LH> connector

Q. Is the check result normal?
Go to Step 13.
Repair the defective connector.

STEP 13. Wiring harness check between A-14 ASC-ECU connector terminal No.33 and C-15 rear wheel speed sensor <LH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.20 and C-15 rear wheel speed sensor <LH> connector terminal No.1.
Check for short circuit in rear wheel speed sensor <LH> circuit

Q. Is the check result normal?
Replace the wheel speed sensor <RL> (Refer to ).
Repair the wiring harness.

STEP 14. Voltage measurement at the A-14 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ABS check harness (MB992335) to the ASC-ECU-side connector and harness-side connector, and then measure the voltage at the special tool connector side.
(2)Turn the electric motor switch to the "ON" position.
(3)Measure the voltage between the front wheel speed sensor circuit power supply terminal and the body earth and between the front wheel speed sensor circuit signal terminal and the body earth.
Diagnosis code No.
 Check terminal
Power supply terminal
 Signal terminal
C1200
 No. 18
 No. 6
C1205
 No. 34
 No. 22
C1210
 No. 19
 No. 31
C1215
 No. 33
 No. 20
OK:
    Approximately system voltage <Power supply terminal>
    0.4 - 1.3V <Signal terminal>

Q. Is the check result normal?

Go to Step 23.

NO (Not normal at the terminal No. 18 or 6) : Go to Step 15

NO (Not normal at the terminal No. 34 or 22) : Go to Step 17.

NO (Not normal at the terminal No. 19 or 31) : Go to Step 19.

NO (Not normal at the terminal No. 33 or 20) : Go to Step 21.

STEP 15. Connector check: A-14 ASC-ECU connector, A-21 front wheel speed sensor <RH> connector

Q. Is the check result normal?
Go to Step 16.
Repair the defective connector.

STEP 16. Wiring harness check between A-14 ASC-ECU connector terminal No.18 and A-21 front wheel speed sensor <RH> connector terminal No.2, and between A-14 TCL/ASC-ECU connector terminal No.6 and A-21 front wheel speed sensor <RH> connector terminal No.1.
Check for open circuit in front wheel speed sensor <RH> circuit.

Q. Is the check result normal?
Go to Step 23.
Repair the wiring harness.

STEP 17. Connector check: A-14 ASC-ECU connector, A-18 front wheel speed sensor <LH> connector

Q. Is the check result normal?
Go to Step 18.
Repair the defective connector.

STEP 18. Wiring harness check between A-14 ASC-ECU connector terminal No.34 and A-18 front wheel speed sensor <LH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.22 and A-18 front wheel speed sensor <LH> connector terminal No.1.
Check for open circuit in front wheel speed sensor <LH> circuit.

Q. Is the check result normal?
Go to Step 23.
Repair the wiring harness.

STEP 19. Connector check: A-14 ASC-ECU connector, B-27 intermediate connector, C-27 rear wheel speed sensor <RH> connector

Q. Is the check result normal?
Go to Step 20.
Repair the defective connector.

STEP 20. Wiring harness check between A-14 ASC-ECU connector terminal No.19 and C-27 rear wheel speed sensor <RH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.31 and C-27 rear wheel speed sensor <RH> connector terminal No.1.
Check for open circuit in rear wheel speed sensor <RH> circuit.

Q. Is the check result normal?
Go to Step 23.
Repair the wiring harness.

STEP 21. Connector check: A-14 ASC-ECU connector, A-107 intermediate connector, C-15 rear wheel speed sensor <LH> connector

Q. Is the check result normal?
Go to Step 22.
Repair the defective connector.

STEP 22. Wiring harness check between A-14 ASC-ECU connector terminal No.33 and C-15 rear wheel speed sensor <LH> connector terminal No.2, and between A-14 ASC-ECU connector terminal No.20 and C-15 rear wheel speed sensor <LH> connector terminal No.1.
Check for open circuit in rear wheel speed sensor <LH> circuit.

Q. Is the check result normal?
Go to Step 23.
Repair the wiring harness.

STEP 23. Check for wheel speed sensor as a single unit
Refer to .

Q. Is the check result normal?
Go to Step 24.
Replace the wheel speed sensor (Refer to ).

STEP 24. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the electric motor switch to the "LOCK" (OFF) position.
(3)Turn the electric motor switch to the "ON" position.
(4)Start the electric motor unit.

Q. Is the diagnosis code No.C1200, C1205, C1210, C1215 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).