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DTC C1046 FL Wheel Speed Sensor Phase
DTC C1047 FR Wheel Speed Sensor Phase
DTC C1048 RL Wheel Speed Sensor Phase
DTC C1049 RR Wheel Speed Sensor Phase
 
 
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 Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
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.
 
 
 
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.
 
 
 
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:
  • MB991223: Harness Set
STEP 1. Using scan tool (M.U.T.-IIISE), check other DTC.
Check that DTC C100A, C1015, C1020 or C102B is also set.
Is DTC C100A, C1015, C1020 or C102B also set?
Perform the diagnosis for DTC C100A, C1015, C1020 or C102B (Refer to ).
Go to Step 2.
 
STEP 2. Check the wiring harness between the ASC-ECU connector terminal and the wheel speed sensor connector terminal
DTC C1046 is set
  • Check of short to ground and open circuit in FL+, FL- line between ASC-ECU connector and front wheel speed sensor (LH) connector.
DTC C1047 is set
  • Check of short to ground and open circuit in FR+, FR- line between ASC-ECU connector and front wheel speed sensor (RH) connector.
DTC C1048 is set
  • Check of short to ground and open circuit in RL+, RL- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
DTC C1049 is set
  • Check of short to ground and open circuit in RR+, RR- line between ASC-ECU connector and rear wheel speed sensor (RH) connector.
Is the check result normal?
Go to Step 3.
Repair the connector(s) or wiring harness.
 
STEP 3. Check for wheel speed sensor installation
Check how the wheel speed sensor is installed (Disconnection of wheel speed sensor, loose mounting bolt, etc.).
Is the check result normal?
Go to Step 4.
Reinstall the wheel speed sensor correctly [Refer to (Front) or (Rear)].
 
STEP 4. Check for wheel speed sensor output current
Refer to .
Is the check result normal?
Go to Step 5.
Replace the wheel speed sensor [Refer to (Front) or (Rear)].
 
STEP 5. Check for wheel bearing looseness
noteLoose wheel bearing may increase the gap between the wheel speed sensor and the wheel speed detection magnet encoder. Check the wheel bearing for looseness. [Refer to GROUP 26 - Wheel Bearing Axial Play Check (Front), GROUP 27A - Wheel Bearing Axial Play Check (Rear) <FWD>, GROUP 27B - Wheel Bearing Axial Play Check (Rear) <AWD>].
Is the check result normal?
Go to Step 6.
Replace the wheel bearing (Front) or rear wheel hub assembly (Rear) [Refer to GROUP 26 - Front Axle Hub Assembly (Front), GROUP 27A - Rear Axle Hub Assembly (Rear) <FWD>, GROUP 27B - Rear Axle Hub Assembly (Rear) <AWD>].
 
STEP 6. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or deformation.
Is the check result normal?
Go to Step 7.
: 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.
: Replace the wheel bearing (Front) or rear wheel hub assembly (Rear) [Refer to GROUP 26 - Front Axle Hub Assembly (Front), GROUP 27A - Rear Axle Hub Assembly (Rear) <FWD>, GROUP 27B - Rear Axle Hub Assembly (Rear) <AWD>].
 
STEP 7. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position.
(4) Drive the vehicle at 20 km/h (12 mph) or higher.
noteThe ABS warning light does not turn OFF in some cases unless the vehicle runs at 20 km/h (12 mph) or higher.
Is DTC C1046, C1047, C1048 or C1049 set?
Replace the wheel speed sensor [Refer to (Front) or (Rear)]. Then go to Step 8.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 8. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position.
(4) Drive the vehicle at 20 km/h (12 mph) or higher.
noteThe ABS warning light does not turn OFF in some cases unless the vehicle runs at 20 km/h (12 mph) or higher.
Is DTC C1046, C1047, C1048 or C1049 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
This diagnosis is complete.