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Code No. C1201 FR wheel speed sensor signal
Code No. C1206 FL wheel speed sensor signal
Code No. C1211 RR wheel speed sensor signal
Code No. C1216 RL wheel speed sensor signal
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be stored. 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.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).
 
 
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.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
ASC-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, ASC-ECU will store the relevant diagnostic trouble code.
  • Irregular change in the wheel speed sensor signal
  • Wheel speed sensor signal continuously indicates high value.
 
 
PROBABLE CAUSES
Current trouble
  • Improper installation of the wheel speed sensor
  • Malfunction of the wheel speed sensor
  • Adhesion of foreign materials on the wheel speed sensor
  • Wheel bearing malfunction
  • Excessive gap between the wheel speed sensor and the wheel speed detection encoder
  • Adhesion of foreign materials on the wheel speed detection magnetic encoder
  • Deformation of the wheel speed detection magnetic encoder
  • Disturbance of magnetization pattern for wheel speed detection encoder
  • Terminal quantity error of wheel speed detection encoder
  • Damaged harness wires and connectors
  • Malfunction of ASC-ECU
  • External noise interference
Past trouble
  • When diagnostic trouble code No. C1200, C1205, C1210 or C1215 is also stored, carry out diagnosis with particular emphasis on wiring harness and connector failures between ASC-ECU and wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).
  • When diagnostic trouble code No. C1200, C1205, C1210, or C1215 is not stored, the following causes may be present:
    • Wheel(s) spinning
    • Unstable vehicle attitude
    • External noise interference
    • Vehicle ran with the parking brake applied.
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use the scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting .) On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Is diagnostic trouble code No. C1201, C1206, C1211 or C1216 stored?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Using scan tool MB991958, DTC check.
Check that diagnostic trouble codes No. C1200, C1205, C1210, and C1215 are also stored.
Are diagnostic trouble codes No. C1200, C1205, C1210 and C1215 also stored?
Follow the diagnosis procedure for diagnostic trouble code No. C1200, C1205, C1210 or C1215 (Refer to ).
Go to Step 4.
 
STEP 4. Check whether the wheel speed sensors are installed properly.
Check whether the wheel speed sensor relevant to code No. is installed correctly (sensor dislocation, loose mounting bolt, etc.).
 
Diagnostic trouble code No. Relevant sensor
C1201Front right
C1206Front left
C1211Rear right
C1216Rear left
Is the check result normal?
Go to Step 5.
Install the wheel speed sensor properly (Refer to ).
 
STEP 5. Check the wheel speed sensor.
Refer to .
Is the check result normal?
Go to Step 6.
Replace the wheel speed sensor (Refer to ).
 
STEP 6. 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 indicated by the code No. for looseness.
 
Diagnostic trouble code No. Relevant sensor
C1201Front right
C1206Front left
C1211Rear right
C1216Rear left
  • Front: Refer to GROUP 26 - On-vehicle Service .
  • Rear: Refer to GROUP 27 - On-vehicle Service .
Is the check result normal?
Go to Step 7.
<when the relevant wheel is front> : Replace the wheel bearing (Refer to GROUP 26 - Front Axle Hub Assembly ).
<when the relevant wheel is rear> : Replace the wheel bearing (Refer to GROUP 27 - Rear Axle Hub Assembly ).
 
STEP 7. Check of wheel speed detection encoder
Check the wheel speed detection magnetic encoder for adhesion of foreign materials or deformation.
Is the check result normal?
Go to Step 8.
<when the relevant wheel is front> : 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. If deformation is found, replace the wheel bearing (Refer to GROUP 26 - Front Axle Hub Assembly ).
<when the relevant wheel is rear> : 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. If deformation is found, replace the wheel bearing (Refer to GROUP 27 - Rear Axle Hub Assembly ).
 
STEP 8. Measure the voltage at the ASC-ECU connector.
(1) Connector check: ASC-ECU connector and wheel speed sensor connectors
(2) Disconnect the connector, and measure at the wiring harness side.
(3) Ignition switch: "ON"
(4) Measure the voltage between the power supply terminal as well as signal terminal of each wheel speed sensor circuit and body ground.
 
Diagnostic trouble code No. Checking terminal
Power supply terminalSignal terminal
C1201FR+FR-
C1206FL+FL-
C1211RR+RR-
C1216RL+RL-
OK: 1 V or less
Is the check result normal?
Go to Step 9.
(No. C1201 NG) : Go to Step 11.
(No. C1206 NG) : Go to Step 12.
(No. C1211 NG) : Go to Step 13.
(No. C1216 NG) : Go to Step 14.
 
STEP 9. Measure the resistance at the ASC-ECU connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the power supply terminal as well as signal terminal of each wheel speed sensor circuit and body ground.
 
Diagnostic trouble code No. Checking terminal
Power supply terminalSignal terminal
C1201FR+FR-
C1206FL+FL-
C1211RR+RR-
C1216RL+RL-
OK: No continuity
Is the check result normal?
Go to Step 10.
(No. C1201 NG) : Go to Step 11.
(No. C1206 NG) : Go to Step 12.
(No. C1211 NG) : Go to Step 13.
(No. C1216 NG) : Go to Step 14.
 
STEP 10. Measure the voltage at the ASC-ECU connector.
(1) Measure with the connector(s) connected.
(2) Ignition switch: "ON"
(3) Measure the voltage between the power supply terminal as well as signal terminal of each wheel speed sensor circuit and body ground.
 
Diagnostic trouble code No. Checking terminal
Power supply terminalSignal terminal
C1201FR+FR-
C1206FL+FL-
C1211RR+RR-
C1216RL+RL-
OK:
  • Power supply terminal: Approx. system voltage
  • Signal terminal: approximately 0.4 to 1.3 V
Is the check result normal?
Go to Step 15.
(No. C1201 NG) : Go to Step 11.
(No. C1206 NG) : Go to Step 12.
(No. C1211 NG) : Go to Step 13.
(No. C1216 NG) : Go to Step 14.
 
STEP 11. Check the wiring harness wires between the ASC-ECU connector FR (+) or FR (-) terminal and the front wheel speed sensor (RH) connector terminal.
Check the front wheel speed sensor (RH) circuit for short and open.
Is the check result normal?
Go to Step 15.
Repair the connector(s) and wiring harness.
 
STEP 12. Check the wiring harness wires between the ASC-ECU connector FL (+) or FL (-) terminal and the front wheel speed sensor (LH) connector terminal.
Check the front wheel speed sensor (LH) circuit for short and open.
Is the check result normal?
Go to Step 15.
Repair the connector(s) and wiring harness.
 
STEP 13. Check the wiring harness wires between the ASC-ECU connector RR (+) or RR (-) terminal and the rear wheel speed sensor (RH) connector terminal.
Check the rear wheel speed sensor (RH) circuit for short and open.
Is the check result normal?
Go to Step 15.
Repair the connector(s) and wiring harness.
 
STEP 14. Check the wiring harness wires between ASC-ECU connector RL (+) or RL (-) terminal and the rear wheel speed sensor (LH) connector terminal.
Check the rear wheel speed sensor (LH) circuit for short and open.
Is the check result normal?
Go to Step 15.
Repair the connector(s) and wiring harness.
 
STEP 15. Diagnostic trouble code recheck
Check again if the diagnostic trouble code is stored.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: LOCK (OFF) position to ON
(3) Drive the vehicle until the vehicles speed reaches 20 km/h.
Is diagnostic trouble code No. C1201, C1206, C1211 or C1216 stored?
Replace the wheel speed sensor (Refer to ). Then go to Step 16.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
 
STEP 16. Diagnostic trouble code recheck
Check again if the diagnostic trouble code is stored.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: LOCK (OFF) position to ON
(3) Drive the vehicle until the vehicles speed reaches 20 km/h.
Is diagnostic trouble code No. C1201, C1206, C1211 or C1216 stored?
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to .)
This diagnosis is complete.