Code No. C1032 Abnormality in RR wheel speed sensor signal














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, Trouble code diagnosis ).

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

DIAGNOSIS CODE SET CONDITIONS
ASC-ECU monitors the signals from each wheel speed sensor while the vehicle is being driven. If any fault below is found in these sensor signals, ASC-ECU will set the relevant diagnosis code.

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

PROBABLE CAUSES
Current trouble
  • 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
  • ASC-ECU malfunction
  • Disturbance of magnetisation pattern for wheel speed detection encoder
Past trouble
  • When the diagnosis code No. C102B is also set, 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 Cope with Intermittent Malfunction ).
  • When the diagnosis code No. C102B is not set, the following conditions may be present:

    • Right or/and left wheels are rotated.
    • Unstable vehicle attitude
    • External noise interference
    • Vehicle ran with the parking brake applied.

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 - Troubleshooting ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines

Q. Is the diagnosis code No. C1032 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Check that the diagnosis code No. C102B is also set.

Q. Is the diagnosis code No. C102B also set?
Perform the diagnosis for the diagnosis code No. C102B (Refer to ).
Go to Step 4.

STEP 4. Check for wheel speed sensor installation
Check how the wheel speed sensor <RR> is installed (Disconnection of wheel speed sensor, loose mounting bolt, etc.).

Q. Is the check result normal?
Go to Step 5.
Reinstall the wheel speed sensor correctly.

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

Q. Is the check result normal?
Go to Step 6.
Replace the wheel speed sensor.

STEP 6. Check for wheel bearing looseness
note Loose wheel bearing may increase the gap between the wheel speed sensor and the wheel speed detection magnet encoder. Check the wheel bearing <RR> for looseness (Refer to GROUP 27B - On-vehicle Service ).

Q. Is the check result normal?
Go to Step 7.
Replace the rear wheel hub assembly.

STEP 7. Check of wheel speed detection encoder

Check the encoder for adhesion of foreign materials or deformation.

Q. Is the check result normal?

Go to Step 8.

Remove the foreign materials and clean the encoder so as not to disturb the magnetisation pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. When the encoder is deformed, replace the rear hub assembly.

STEP 8. Voltage measurement at the A-03 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the voltage at the special tool connector side.
note Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.
(2)Turn the ignition switch to the ON position.
(3)Measure the voltage between the wheel speed sensor power supply terminal (signal terminal) No. 43/the earth terminal No. 42 and the body earth.
OK: 0 V

Q. Is the check result normal?

Go to Step 9.

NO (Not normal at terminal 43 or 42) : Go to Step 10.

STEP 9. Resistance measurement at A-03 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.
note Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.
(2)Resistance between the wheel speed sensor power supply terminal (signal terminal) No. 43/the earth terminal No. 42 and the body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 11.

NO (Not normal at terminal 43 or 42) : Go to Step 10.

STEP 10. Connector check: A-03 ASC-ECU connector, C-131 intermediate connector, D-109 wheel speed sensor <RR> connector

Q. Is the check result normal?
The short circuit in the wheel speed sensor <RR> circuit may be present. Repair the wiring harness between the A-03 ASC-ECU connector terminal No. 43/42 and the D-109 wheel speed sensor <RR> connector terminal No. 1/2.
Repair the defective connector.

STEP 11. Voltage measurement at the A-03 ASC-ECU connector

(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the ASC-ECU-side connector and harness-side connector, and then measure the voltage at the special tool connector side.
(2)Turn the ignition switch to the ON position.
(3)Measure the voltage between the wheel speed sensor circuit power supply terminal (signal terminal) No. 43 and the body earth.
OK: Approximately battery voltage

Q. Is the check result normal?

Go to Step 12.

Replace the ASC-ECU.

STEP 12. Connector check: A-03 ASC-ECU connector, C-131 intermediate connector, D-109 wheel speed sensor <RR> connector

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

STEP 13. Wiring harness check between A-03 ASC-ECU connector terminal No. 43/42 and D-109 wheel speed sensor <RR> connector terminal No. 1/2

  • Check for open circuit in wheel speed sensor <RR> circuit

Q. Is the check result normal?
Go to Step 14.
Repair the wiring harness.

STEP 14. Check whether the diagnosis code is reset.
Drive the vehicle at 20 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is the diagnosis code No. C1032 set?
Replace the ASC-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).