Code No.C1207: Wheel speed sensor (FL) (malfunction power 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 .).
  • Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION



  • A toothed ABS rotor generates a pulse signal as it moves across the pickup field of each wheel speed sensor.
  • The wheel speed sensor transmit the frequency of the pulses to the ASTC-ECU.
  • The hydraulic unit assembly (integrated with ASTC-ECU) modulates the amount of braking force individually applied to each wheel cylinder.

DIAGNOSIS CODE SET CONDITION



PROBABLE CAUSES


Current trouble
  • Damaged wiring harness and connectors
  • Noise interference
  • Wheel speed sensor malfunction
  • ASTC-ECU malfunction
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASTC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - 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
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.

Q. Is the diagnosis code No.C1207 set?
Go to Step 3.
This diagnosis is complete.

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

  • Item No.01: FL wheel speed sensor

Q. Is the check result normal?
Go to Step 8.
Go to Step 4.

STEP 4. Connector check: A-48 ASTC-ECU connector, A-119 front wheel speed sensor (LH) connector

Q. Is the check result normal?
Go to Step 5.
Repair the defective connector. Then go to Step 9.

STEP 5. Voltage measurement at the A-48 ASTC-ECU connector
(1)Disconnect the A-48 ASTC-ECU connector, the A-119 front wheel speed sensor (LH) connector.
(2)Measure the voltage between the A-48 ASTC-ECU connector terminal No.18 and body earth.
OK: 1V or less

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness. Then go to Step 9.

STEP 6. Resistance measurement at the A-48 ASTC-ECU connector
(1)Disconnect the A-48 ASTC-ECU connector, the A-119 front wheel speed sensor connector.
(2)Measure the resistance between the A-48 ASTC-ECU connector terminal No.18 and body earth.
OK: No continuity

Q. Is the check result normal?
Go to Step 7.
Repair the wiring harness. Then go to Step 9.

STEP 7. Check for wheel speed sensor as a single unit
Refer to .

Q. Is the check result normal?
Go to Step 8.
Replace the wheel speed sensor (Refer to .). Then go to Step 9.

STEP 8. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.

Q. Is the diagnosis code No.C1207 set?
Replace the hydraulic unit (integrated with ASTC-ECU) (Refer to .). Then go to Step 9.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions .).

STEP 9. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.

Q. Is the diagnosis code No.C1207 set?
Return to Step 1.
This diagnosis is complete.