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DTC C102B Abnormality in RR wheel speed sensor circuit
 
 
 
 
caution
  • 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 (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).
  • 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, the G and yaw rate sensor and brake fluid pressure 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.
 
 
 
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 diagnostic trouble code.
 
 
 
PROBABLE CAUSES
Current trouble
  • Damaged wiring harness and connectors
  • Noise interference
  • Malfunction of wheel speed sensor
  • ASC-ECU malfunction
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 ).
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
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 the ignition switch from the ON position to the LOCK (OFF) position.
Is DTC C102B set?
Go to Step 3.
The procedure is complete.
 
STEP 3. Using scan tool MB991958, check data list
Check the following data list (Refer to ).
  • Item No.04: RR wheel speed sensor
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction ).
Go to Step 4.
 
STEP 4. Voltage measurement at the A-03 ASC-ECU connector (Short circuit to power supply)
(1) Disconnect the ASC-ECU connector, connect special tool test harness (MB991709) to the harness-side connector, and then measure the voltage at the special tool connector side.
noteDo not connect the special tool to ASC-ECU.
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the wheel speed sensor power supply terminal (signal terminal) No.34 and the body ground and between the wheel speed sensor ground terminal No.33 and the body ground.
OK: 1 Volt or less
Is the check result normal?
Go to Step 5.
(Not normal at the terminal No.34 or 33) : Go to Step 6.
 
STEP 5. Resistance measurement at A-03 ASC-ECU connector (Short circuit to ground)
(1) Disconnect the ASC-ECU connector, connect special tool test harness (MB991709) to the harness-side connector, and then measure the resistance at the special tool connector side.
noteDo not connect the special tool to ASC-ECU.
(2) Measure the resistance between the wheel speed sensor power supply terminal (signal terminal) No.34 and the body ground and between the wheel speed sensor ground terminal No.33 and the body ground.
OK: No continuity
Is the check result normal?
Go to Step 8.
(Not normal at the terminal No.34 or 33) : Go to Step 6.
 
STEP 6. Connector check: A-03 ASC-ECU connector, C-15 intermediate connector, D-15 rear wheel speed sensor <RH> connector
Is the check result normal?
Go to Step 7.
Repair the defective connector.
 
STEP 7. Wiring harness check between A-03 ASC-ECU connector terminal No.34 and D-15 rear wheel speed sensor <RH> connector terminal No.1 and between A-03 ASC-ECU connector terminal No.33 and D-15 rear wheel speed sensor <RH> connector terminal No.2
  • Check for short circuit in rear wheel speed sensor <RH> circuit for short to power supply or ground.
Is the check result normal?
Replace the wheel speed sensor <RR> (Refer to ).
Repair the wiring harness.
 
STEP 8. Voltage and current measurement at D-15 rear wheel speed sensor <RH> connector (Open circuit)
(1) Disconnect the D-15 rear wheel speed sensor <RH> connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the power supply terminal of D-15 rear wheel speed sensor <RH> connector terminal No. 1 and the body ground.
(4) Measure the output current at the special tool test harness (MB991709) to connect between the D-15 rear wheel speed sensor <RH> 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 9.
 
STEP 9. Wiring harness check between A-03 ASC-ECU connector terminal No.34 and D-15 rear wheel speed sensor <RH> connector terminal No.1 and between A-03 ASC-ECU connector terminal No.33 and D-15 rear wheel speed sensor <RH> connector terminal No.2.
  • Check for open circuit in rear wheel speed sensor <RH> circuit
Is the check result normal?
Go to Step 10.
Repair the wiring harness.
 
STEP 10. Check for wheel speed sensor <RR> as a single unit
Refer to .
Is the check result normal?
Go to Step 11.
Replace the wheel speed sensor <RR> (Refer to ).
 
STEP 11. Connector check: A-03 ASC-ECU connector, D-15 rear wheel speed sensor <RH> connector
Is the check result normal?
Go to Step 12.
Repair the defective connector.
 
STEP 12. Check whether the diagnostic trouble code is set again.
(1) Erase the diagnostic trouble code.
(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 C102B set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).