C1015
DTC C1015 Abnormality in FR 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 CAN Bus Line Diagnostics 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 Testing and Inspection , Testing and Inspection and Testing and Inspection ).
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 (How to Use Troubleshooting/How to Treat Past Trouble 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.
Q. Is the check result normal?
YES Go to Step 3.
NO Repair the CAN bus lines CAN Bus Line Diagnostics Flow).
On completion, go to Step 2.
STEP 2. DTC recheck after resetting CAN bus lines
Q. Is DTC C1015 set?
YES Go to Step 3.
NO The procedure is complete.
STEP 3. Using scan tool MB991958, check data list
Check the following data list (Refer to Data List Reference Table).
- Item No.02: FR wheel speed sensor
Q. Is the check result normal?
YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Go to Step 4.
STEP 4. Voltage measurement at the A-03 ASC-ECU connector
(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the voltage at the special tool connector side.
NOTE:
Do 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
Q. Is the check result normal?
YES Go to Step 5.
NO (Not normal at the terminal No.34 or 33) : Go to Step 6.
STEP 5. Resistance measurement at A-03 ASC-ECU connector
(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.
NOTE:
Do 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
Q. Is the check result normal?
YES Go to Step 8.
NO (Not normal at the terminal No.34 or 33) : Go to Step 6.
STEP 6. Connector check: A-03 ASC-ECU connector, A-02 front wheel speed sensor [RH]
connector
Q. Is the check result normal?
YES Go to Step 7.
NO Repair the defective connector.
STEP 7. Wiring harness check between A-03 ASC-ECU connector terminal No.34 and A-02 front wheel speed sensor [RH]
connector terminal No.1 and between A-03 ASC-ECU connector terminal No.33 and A-02 front wheel speed sensor [RH]
connector terminal No.2.
- Check for short circuit in front wheel speed sensor[ RH] circuit
Q. Is the check result normal?
YES Replace the wheel speed sensor [FR]
(Refer to Service and Repair).
NO Repair the wiring harness.
STEP 8. Voltage measurement at the A-03 ASC-ECU connector
(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the ASC-ECU-side connector and harness-side connector, and then measure the voltage at the special tool connector side.
(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 body ground, and between the ground terminal No.33 and body ground.
OK:
Terminal No.34 and body ground: Approximately system voltage
Terminal No.33 and body ground: 1 volt or less
Q. Is the check result normal?
YES Go to Step 9.
NO Go to Step 11.
STEP 9. Wiring harness check between A-03 ASC-ECU connector terminal No.34 and A-02 front wheel speed sensor [RH]
connector terminal No.1 and between A-03 ASC-ECU connector terminal No.33 and A-02 front wheel speed sensor [RH]
connector terminal No.2.
- Check for open circuit in front wheel speed sensor[ RH] circuit.
Q. Is the check result normal?
YES Go to Step 10.
NO Repair the wiring harness.
STEP 10. Check for wheel speed sensor [FR]
as a single unit
Refer to Wheel Speed Sensor Inspection.
Q. Is the check result normal?
YES Go to Step 11.
NO Replace the wheel speed sensor [FR]
(Refer to Service and Repair).
STEP 11. Connector check: A-03 ASC-ECU connector, A-02 front wheel speed sensor [RH]
connector
Q. Is the check result normal?
YES Go to Step 12.
NO Repair the defective connector.
STEP 12. Check whether the diagnostic trouble code is reset.
(1)Erase the diagnostic trouble code.
(2)Drive the vehicle at 12 mph (20 km/h) or higher.
NOTE:
The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph
(20 km/h) or higher.
Q. Is DTC C1015 set?
YES Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Service and Repair).
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).