C1041
DTC C1041 Abnormality in periodical signal for FL wheel speed sensorCAUTION
^ 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 Diagnostic trouble code diagnosis Diagnostic Trouble Code Descriptions).
^ 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.
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
ASC-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, ASC-ECU will set the relevant DTC.
PROBABLE CAUSES
^ Wheel bearing malfunction
^ Deformation of the wheel speed detection encoder
^ Missing teeth of the wheel speed detection encoder
^ Adhesion of foreign materials on the wheel speed detection encoder
^ ASC-ECU malfunction
^ The number of poles on the Magnetic encoder for wheel speed detection (N-pole and S-pole) is changed
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?
YES: Go to Step 3.
NO: Repair the CAN bus lines (Refer to Diagnosis - CAN Bus Diagnostic Table CAN Bus Diagnostics Table). On completion, go to Step 2.
STEP 2. DTC recheck after resetting CAN bus lines
Q: Is DTC C1041 set?
YES: Go to Step 3.
NO: The procedure is complete.
STEP 3. 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 [FL] for looseness.
Q: Is the check result normal?
YES: Go to Step 4.
NO: Replace the wheel bearing.
STEP 4. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or deformation.
Q: Is the check result normal?
YES: Go to Step 5.
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. When the encoder is deformed, replace the wheel bearing.
NO (Deformation): Replace the wheel bearing.
STEP 5. Check whether the DTC is reset.
1. Erase the DTC.
2. Drive the vehicle at 12 mph (20 km/h) or more.
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 C1041 set?
YES: Replace the hydraulic unit (ASC-ECU). Then go to Step 6.
NO: Intermittent malfunction.
STEP 6. Check whether the DTC is reset.
1. Erase the DTC.
2. Drive the vehicle at 12 mph (20 km/h) or more.
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 C1041 set?
YES: Return to Step 1.
NO: The procedure is complete.