C1014
DTC C1014: Mutual monitoring of FL wheel speed sensorCAUTION
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
CIRCUIT OPERATION
^ The wheel speed sensor is a type of 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 fault below is found in these sensor signals, ABS-ECU will set the relevant diagnostic trouble code.
^ Missing wheel speed sensor signal
^ Wheel speed sensor signal continuously indicates lower value than the values of other wheel speed sensors.
PROBABLE CAUSES
Current trouble
^ Excessive gap between the wheel speed sensor and the magnetic encoder for wheel speed detection
^ Wheel bearing malfunction
^ Deformation of 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
^ 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 C100A is also set, carry out diagnosis with particular emphasis on wiring harness and connector failures between ABS-ECU and the wheel speed sensor.
^ When the diagnostic trouble code C100A 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.
^ Only two wheels are rotated on a drum tester.
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
^ MB991974: ABS check harness
STEP 1. M.U.T.-III CAN bus diagnostics
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. On completion, go to Step 2.
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C1014 set?
YES: Go to Step 3.
NO: The procedure is complete.
STEP 3. M.U.T.-III diagnostic trouble code
Check that the diagnostic trouble code C100A is also set.
Q: Is DTC C100A also set?
YES: Perform the diagnosis for the diagnostic trouble code C100A. C100A
NO: Go to Step 4.
STEP 4. Check wheel speed sensor installation
Check how the wheel speed sensor [FL] is installed (Disconnection of wheel speed sensor, loose mounting bolt, etc.).
Q: Is the check result normal?
YES: Go to Step 5.
NO: Reinstall the wheel speed sensor correctly.
STEP 5. Check for wheel speed sensor as a single unit
Q: Is the check result normal?
YES: Go to Step 6.
NO: 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 [FL] for looseness.
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the wheel bearing.
STEP 7. Check wheel speed detection encoder
Check the encoder for adhesion of foreign materials or deformation.
Q: Is the check result normal?
YES: 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.
NO (Deformation): Replace the wheel bearing.
STEP 8. Check whether the diagnostic trouble code is reset.
1) Erase the diagnostic trouble code.
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 C1014 set?
YES: Replace the ABS-ECU.
NO: Intermittent malfunction.