Code No. C100A FL wheel speed sensor circuit
Code No. C1015 FR wheel speed sensor circuit
Code No. C1020 RL wheel speed sensor circuit
Code No. C102B RR wheel speed sensor circuit


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code 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.

DIAGNOSIS CODE SET CONDITIONS
ASC-ECU monitors the voltage fluctuation in each wheel speed sensor circuit. If ASC-ECU detects the open or short circuit in the circuit, it will set a diagnosis code.

PROBABLE CAUSES
Current trouble
  • Damaged wiring harness and connectors
  • Noise interference
  • Malfunction of wheel speed sensor
  • Malfunction of ASC-ECU
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ).

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III 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. Diagnosis code recheck after resetting CAN bus lines

Q. Is diagnosis code No. C100A, 1015, 1020 or 102B set?
Go to Step 3
This diagnosis is complete.

STEP 3. M.U.T.-III data list
Check the following data list (Refer to ).

  • Item No.01: FL wheel speed sensor
  • Item No.02: FR wheel speed sensor
  • Item No.03: RL wheel speed sensor
  • Item No.04: RR wheel speed sensor

Q. Is the check result normal?
Go to Step 10
Go to Step 4

STEP 4. Voltage measurement at the ASC-ECU connector (FL+, FL-, FR+, FR-, RL+, RL-, RR+, RR- terminal)
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the ON position.
Code No.C100A is set
  • Measure the voltage between the ASC-ECU connector (FL+ terminal) and the body earth, and between the ASC-ECU connector (FL- terminal) and the body earth.
OK: 1 V or less
Code No.C1015 is set
  • Measure the voltage between the ASC-ECU connector (FR+ terminal) and the body earth, and between the ASC-ECU connector (FR- terminal) and the body earth.
OK: 1 V or less
Code No.C1020 is set
  • Measure the voltage between the ASC-ECU connector (RL+ terminal) and the body earth, and between the ASC-ECU connector (RL- terminal) and the body earth.
OK: 1 V or less
Code No.C102B is set
  • Measure the voltage between the ASC-ECU connector (RR+ terminal) and the body earth, and between the ASC-ECU connector (RR- terminal) and the body earth.
OK: 1 V or less

Q. Is the check result normal?
Go to Step 5
Go to Step 6

STEP 5. Resistance measurement at ASC-ECU connector (FL+, FL-, FR+, FR-, RL+, RL-, RR+, RR- terminal)
Disconnect the connector, and measure at the wiring harness side.
Code No.C100A is set
  • Measure the resistance between the ASC-ECU connector (FL+ terminal) and the body earth, and between the ASC-ECU connector (FL- terminal) and the body earth.
OK: No continuity
Code No.C1015 is set
  • Measure the resistance between the ASC-ECU connector (FR+ terminal) and the body earth, and between the ASC-ECU connector (FR- terminal) and the body earth.
OK: No continuity
Code No.C1020 is set
  • Measure the resistance between the ASC-ECU connector (RL+ terminal) and the body earth, and between the ASC-ECU connector (RL- terminal) and the body earth.
OK: No continuity
Code No.C102B is set
  • Measure the resistance between the ASC-ECU connector (RR+ terminal) and the body earth, and between the ASC-ECU connector (RR- terminal) and the body earth.
OK: No continuity

Q. Is the check result normal?
Go to Step 7
Go to Step 6

STEP 6. Check the wiring harness between the ASC-ECU connector terminal and the wheel speed sensor connector terminal.
Code No.C100A is set
  • Check of short circuit in FL+, FL- line between ASC-ECU connector and front wheel speed sensor (LH) connector.
Code No.C1015 is set
  • Check of short circuit in FR+, FR- line between ASC-ECU connector and front wheel speed sensor (RH) connector.
Code No.C1020 is set
  • Check of short circuit in RL+, RL- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
Code No.C102B is set
  • Check of short circuit in RR+, RR- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.

Q. Is the check result normal?
Replace the wheel speed sensor (Refer to <front> or <rear>). Then go to Step 11.
Repair the connector(s) or wiring harness. Then go to Step 11.

STEP 7. Resistance measurement at the ASC-ECU connector (FL+, FL-, FR+, FR-, RL+, RL-, RR+, RR- terminal)
Disconnect the connector, and measure at the wiring harness side.
Code No.C100A is set
  • Measure the resistance between the ASC-ECU connector (FL+ terminal) and the ASC-ECU connector (FL- terminal).
OK: Continuity
Code No.C1015 is set
  • Measure the resistance between the ASC-ECU connector (FR+ terminal) and the ASC-ECU connector (FR- terminal).
OK: Continuity
Code No.C1020 is set
  • Measure the resistance between the ASC-ECU connector (RL+ terminal) and the ASC-ECU connector (RL- terminal).
OK: Continuity
Code No.C102B is set
  • Measure the resistance between the ASC-ECU connector (RR+ terminal) and the ASC-ECU connector (RR- terminal).
OK: Continuity

Q. Is the check result normal?
Go to Step 8
Go to Step 10

STEP 8. Check the wiring harness between the ASC-ECU connector terminal and the wheel speed sensor connector terminal
Code No.C100A is set
  • Check of open circuit in FL+, FL- line between ASC-ECU connector and front wheel speed sensor (LH) connector.
Code No.C1015 is set
  • Check of open circuit in FR+, FR- line between ASC-ECU connector and front wheel speed sensor (RH) connector.
Code No.C1020 is set
  • Check of open circuit in RL+, RL- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
Code No.C102B is set
  • Check of open circuit in RR+, RR- line between ASC-ECU connector and rear wheel speed sensor (RH) connector.

Q. Is the check result normal?
Go to Step 9
Repair the connector(s) or wiring harness. Then go to Step 11.

STEP 9. Check for wheel speed sensor as a single unit
Refer to .

Q. Is the check result normal?
Go to Step 10
Replace the wheel speed sensor (Refer to <front> or <rear>). Then go to Step 11.

STEP 10. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or higher.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is diagnosis code No. C100A, 1015, 1020 or 102B set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 11.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).

STEP 11. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or higher.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is diagnosis code No. C100A, 1015, 1020 or 102B set?
Return to Step 1.
This diagnosis is complete.