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DTC C1043: Abnormality in periodical signal for RL wheel speed sensor


caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

CIRCUIT 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.

DTC SET CONDITIONS
ABS-ECU monitors the signals from each wheel speed sensor while the vehicle is being driven. If any periodical drop is found in these sensor signals, ABS-ECU will set the relevant DTC.

PROBABLE CAUSES
Current trouble
  • Excessive gap between the wheel speed sensor and the magnetic encoder for wheel speed detection
  • Adhesion of foreign materials on the wheel speed sensor
  • Wheel bearing malfunction
  • Deformation of the magnetic encoder for wheel speed detection
  • Adhesion of foreign materials on the magnetic encoder for wheel speed detection
  • Malfunction of wheel speed sensor
  • Improper installation of the wheel speed sensor
  • ABS-ECU malfunction
  • Disturbance of magnetization pattern for magnetic encoder for wheel speed detection
  • The number of poles on the magnetic encoder for wheel speed detection (the number of N-pole and S-pole) is changed.
Past trouble
  • When the diagnostic trouble code No. C1020 is also set, carry out diagnosis with particular emphasis on wiring harness and connector failures between ABS-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ).
  • When the diagnostic trouble code No. C1020 is not set, the following conditions may be present:

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

DIAGNOSIS
Required Special Tools:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)

    • MB991824: Vehicle Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool 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. DTC recheck after resetting CAN bus lines

Q. Is DTC C1043 set?
Go to Step 3.
The procedure is complete.

STEP 3. Using scan tool MB991958, check the DTC
Check that the DTC C1020 is also set.

Q. Is DTC C1020 also set?
Perform the diagnosis for the DTC C1020 (Refer to ).
Go to Step 4.

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

Q. Is the check result normal?
Go to Step 5.
Reinstall the wheel speed sensor <RL> correctly (Refer to ). Then go to Step 5.

STEP 5. Check for wheel speed sensor <RL> output current
Refer to .

Q. Is the check result normal?
Go to Step 6.
Replace the wheel speed sensor <RL> (Refer to ). Then go to Step 9.

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

Q. Is the check result normal?
Go to Step 7.
Replace the rear wheel hub assembly <RL> (Refer to GROUP 27A - Rear Axle Hub Assembly ). Then go to Step 10.

STEP 7. Check wheel speed detection encoder

Check the encoder for adhesion of foreign materials or deformation.

Q. Is the check result normal?

Go to Step 8.

NO (Adhesion of foreign materials) : Remove the foreign materials and clean the encoder so as not to disturb the magnetization pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. Then go to Step 10.

NO (Deformation) : Replace the rear wheel hub assembly <RL> (Refer to GROUP 27A - Rear Axle Hub Assembly ). Then go to Step 10.

STEP 8. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12mph (20 km/h) or higher.
note The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.

Q. Is DTC C1043 set?
Replace the wheel speed sensor <RL> (Refer to ). Then go to Step 9.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).

STEP 9. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12mph (20 km/h) or higher.
note The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.

Q. Is DTC C1043 set?
Replace the hydraulic unit (integrated with ABS-ECU) (Refer to ). Then go to Step 10.
The procedure is complete.

STEP 10. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12mph (20 km/h) or higher.
note The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.

Q. Is DTC C1043 set?
Return to Step 1.
The procedure is complete.