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DTC C1046 FL wheel speed sensor control phase time exceeded








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.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor (Refer to , and ).

OPERATION

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

DTC SET CONDITIONS
This DTC is set if any malfunction below is found:

  • When the brake fluid pressure is decreased for a long time.
  • When the brake fluid pressure is held for a long time.
note ASC controls the vehicle based on the wheel speed signal. When the brake fluid pressure is decreased or held for an abnormally long time, the wheel speed sensor signal may have a problem.

PROBABLE CAUSES

  • Damaged wiring harness and connectors
  • External noise interference
  • Malfunction of wheel speed sensor
  • ASC-ECU malfunction
  • Excessive gap between the wheel speed sensor and the magnetic encoder for wheel speed detection
  • Adhesion of foreign materials on the wheel speed sensor
  • Adhesion of foreign materials on the magnetic encoder for wheel speed detection
  • Wheel bearing malfunction
  • Improper installation of the wheel speed sensor
  • Deformation of the magnetic encoder for wheel speed detection
  • Disturbance of magnetization pattern for magnetic encoder for wheel speed detection
  • Missing teeth of the magnetic encoder for wheel speed detection

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 C1046 set?
Go to Step 3.
The procedure is complete.

STEP 3. Using scan tool MB991958, check the DTC
Check that the DTC C100A, C1011, C1014, or C1041 is also set.

Q. Is the DTC C100A, C1011, C1014, or C1041 also set?
Carry out the diagnosis for the relevant DTC.
Go to Step 4.

STEP 4. Using scan tool MB991958, check the 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 11.
Go to Step 5.

STEP 5. Connector check: A-51 ASC-ECU connector, A-07 front wheel speed sensor <LH> connector

Q. Is the check result normal?
Go to Step 6.
Repair the defective connector. Then go to Step 13.

STEP 6. Wiring harness check between A-51 ASC-ECU connector terminal No.45 and A-07 front wheel speed sensor <LH> connector terminal No.1 and between A-51 ASC-ECU connector terminal No.46 and A-07 front wheel speed sensor <LH> connector terminal No.2.

Q. Is the check result normal?
Go to Step 7.
Repair the wiring harness. Then go to Step 13.

STEP 7. Check for wheel speed sensor <FL> installation
Check how the wheel speed sensor <FL> is installed (Disconnection of wheel speed sensor <FL>, loose mounting bolt, etc.).

Q. Is the check result normal?
Go to Step 8.
Reinstall the wheel speed sensor <FL> correctly (Refer to ). Then go to Step 8.

STEP 8. Check for wheel speed sensor <FL> output current
Refer to .

Q. Is the check result normal?
Go to Step 9.
Replace the wheel speed sensor <FL> (Refer to ). Then go to Step 12.

STEP 9. Check for wheel bearing looseness
note
  • Loose wheel bearing may increase the gap between the wheel speed sensor <FL> and the wheel speed detection magnet encoder.
  • Check the wheel bearing <FL> for looseness (Refer to GROUP 26 - Wheel Bearing Play Check ).

Q. Is the check result normal?
Go to Step 10.
Replace the wheel bearing <FL> (Refer to GROUP 26 - Front axle hub assembly ). Then go to Step 13.

STEP 10. 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 11.

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 13.

NO (Deformation) : Replace the wheel bearing <FL> (Refer to GROUP 26 - Front axle hub assembly ). Then go to Step 13.

STEP 11. 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 C1046 set?
Replace the wheel speed sensor <FL> (Refer to ). Then go to Step 12.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).

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

Q. Is DTC C1046 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 13.
The procedure is complete.

STEP 13. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12 mph (20 km/h) or higher.
note The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.

Q. Is DTC C1046 set?
Return to Step 1.
The procedure is complete.