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DTC C100A FL wheel speed sensor circuit
DTC C1015 FR wheel speed sensor circuit
DTC C1020 RL wheel speed sensor circuit
DTC C102B RR wheel speed sensor circuit
 
 
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
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 DTC.
 
 
 
TROUBLESHOOTING HINTS
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 diagnostic procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ).
 
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB991709: Test Harness
  • MB992006: Extra Fine Probe
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn on the power supply mode of the electric motor switch.
(3) Diagnose the CAN bus line.
(4) Turn off the power supply mode of the electric motor switch.
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. DTC recheck after resetting CAN bus lines.
(1) Drive the vehicle at 12 mph (20 km/h) or higher.
noteThe ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.
(2) Turn on the power supply mode of the electric motor switch.
(3) Turn off the power supply mode of the electric motor switch.
Is DTC No. C100A, 1015, 1020 or 102B set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Scan tool (M.U.T.-IIISE) 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
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 on the power supply mode of the electric motor switch.
DTC C100A is set
  • Measure the voltage between the ASC-ECU connector (FL+ terminal) and the body ground, and between the ASC-ECU connector (FL- terminal) and the body ground.
OK: 1 V or less
DTC C1015 is set
  • Measure the voltage between the ASC-ECU connector (FR+ terminal) and the body ground, and between the ASC-ECU connector (FR- terminal) and the body ground.
OK: 1 V or less
DTC C1020 is set
  • Measure the voltage between the ASC-ECU connector (RL+ terminal) and the body ground, and between the ASC-ECU connector (RL- terminal) and the body ground.
OK: 1 V or less
DTC C102B is set
  • Measure the voltage between the ASC-ECU connector (RR+ terminal) and the body ground, and between the ASC-ECU connector (RR- terminal) and the body ground.
OK: 1 V or less
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.
DTC C100A is set
  • Measure the resistance between the ASC-ECU connector (FL+ terminal) and the body ground, and between the ASC-ECU connector (FL- terminal) and the body ground.
OK: No continuity
DTC C1015 is set
  • Measure the resistance between the ASC-ECU connector (FR+ terminal) and the body ground, and between the ASC-ECU connector (FR- terminal) and the body ground.
OK: No continuity
DTC C1020 is set
  • Measure the resistance between the ASC-ECU connector (RL+ terminal) and the body ground, and between the ASC-ECU connector (RL- terminal) and the body ground.
OK: No continuity
DTC C102B is set
  • Measure the resistance between the ASC-ECU connector (RR+ terminal) and the body ground, and between the ASC-ECU connector (RR- terminal) and the body ground.
OK: No continuity
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.
DTC C100A is set
  • Check of short circuit in FL+, FL- line between ASC-ECU connector and front wheel speed sensor (LH) connector.
DTC C1015 is set
  • Check of short circuit in FR+, FR- line between ASC-ECU connector and front wheel speed sensor (RH) connector.
DTC C1020 is set
  • Check of short circuit in RL+, RL- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
DTC C102B is set
  • Check of short circuit in RR+, RR- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
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. Voltage and current measurement at each wheel speed sensors connector.
(1) Disconnect the wheel speed sensor connector, and measure at the wiring harness side.
(2) Turn on the power supply mode of the electric motor switch.
(3) Measure the voltage between the power supply terminal of each wheel speed sensors and the body ground.
(4) Measure the output current at the special tool test harness (MB991709) to connect between the wheel speed sensor-side connector and the wiring harness connector (Refer to ).
OK:
  • <Voltage> System voltage
  • <Current> 5 - 9 mA or 11 - 17 mA
Is the check result normal?
Go to Step 10.
Go to Step 8.
 
STEP 8. Check the wiring harness between the ASC-ECU connector terminal and the wheel speed sensor connector terminal.
DTC C100A is set
  • Check of open circuit in FL+, FL- line between ASC-ECU connector and front wheel speed sensor (LH) connector.
DTC C1015 is set
  • Check of open circuit in FR+, FR- line between ASC-ECU connector and front wheel speed sensor (RH) connector.
DTC C1020 is set
  • Check of open circuit in RL+, RL- line between ASC-ECU connector and rear wheel speed sensor (LH) connector.
DTC C102B is set
  • Check of 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 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 .
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 DTC is set again.
(1) Erase the DTC.
(2) Drive the vehicle at 12 mph (20 km/h) or higher.
noteThe ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.
Is DTC 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 DTC is set again.
(1) Erase the DTC.
(2) Drive the vehicle at 12 mph (20 km/h) or higher.
noteThe ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.
Is DTC No. C100A, 1015, 1020 or 102B set?
Return to Step 1.
This diagnosis is complete.