Posted in Mitsubishi Colt

Code No.C1201 – Abnormality in FR wheel speed sensor signal MMC Colt

 Posted by  Posted on September 27, 2020

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 ABS-ECU. ABS-ECU uses the frequency of the pulse signals to determine the wheel speed.

    • DIAGNOSIS CODE SET CONDITIONS

  • Irregular change in the wheel speed sensor signal
  • Wheel speed sensor signal continuously indicates high value.

    • PROBABLE CAUSES

  • Excessive gap between the wheel speed sensor and the wheel speed detection encoder
  • Adhesion of foreign materials on the wheel speed sensor
  • Adhesion of foreign materials on the wheel speed detection encoder
  • Wheel bearing malfunction
  • Malfunction of wheel speed sensor
  • Damaged wiring harness and connectors
  • External noise interference
  • Improper installation of the wheel speed sensor
  • Deformation of the wheel speed detection encoder
  • ABS-ECU malfunction
  • Disturbance of magnetisation pattern for wheel speed detection encoder
  • The number of poles on the magnetic encoder for wheel speed detection (the number of N-pole and S-pole) is changed.
  • When diagnosis code No.C1200 is not set, the following conditions may be present:
  • Some wheels slip
  • Unstable vehicle attitude
  • External noise interference
  • Vehicle ran with the parking brake applied.

    • DIAGNOSIS PROCEDURE

    STEP 1. M.U.T.-III CAN bus diagnosis

    Q. Is the check result normal?

    STEP 2. Diagnosis code recheck after resetting CAN bus lines

    Q. Is diagnosis code No.C1201 set?

    STEP 3. M.U.T.-III diagnosis code

    Q. Is the diagnosis code No.C1200 also set?

    STEP 4. Check for wheel speed sensor <FR> installation

    Q. Is the check result normal?

    STEP 5. Check for wheel speed sensor <FR> as a single unit

    Q. Is the check result normal?

    STEP 6. Check for wheel bearing looseness

  • Loose wheel bearing may increase the gap between the wheel speed sensor <FR> and the wheel speed detection magnet encoder.

    • Q. Is the check result normal?

    STEP 7. Check of wheel speed detection encoder

    Q. Is the check result normal?

    STEP 8. Voltage measurement at the A-05 ABS-ECU connector

    Q. Is the check result normal?

    STEP 9. Resistance measurement at A-05 ABS-ECU connector

    Q. Is the check result normal?

    STEP 10. Connector check: A-05 ABS-ECU connector, A-02 front wheel speed sensor <RH> connector

    Q. Is the check result normal?

    STEP 11. Wiring harness check between A-05 ABS-ECU connector terminal No.7 and A-02 front wheel speed sensor <RH> connector terminal No.2, and between A-05 ABS-ECU connector terminal No.6 and A-02 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?

    STEP 12. Voltage measurement at the A-05 ABS-ECU connector

    Q. Is the check result normal?

    STEP 13. Connector check: A-05 ABS-ECU connector, A-02 front wheel speed sensor <RH> connector

    Q. Is the check result normal?

    STEP 14. Wiring harness check between A-05 ABS-ECU connector terminal No.7 and A-02 front wheel speed sensor <RH> connector terminal No.2, and between A-05 ABS-ECU connector terminal No.6 and A-02 front wheel speed sensor <RH> connector terminal No.1

  • Check for the open circuit in the front wheel speed sensor <RH> circuit.

    • Q. Is the check result normal?

    STEP 15. Check whether the diagnosis code is reset.

    Q. Is diagnosis code No.C1201 set?

    STEP 16. Check whether the diagnosis code is reset.

    Q. Is diagnosis code No.C1201 set?

    Author: admin