TCS or ASC
DTC C1032: Abnormality in RR wheel speed sensor signal
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.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve.
CIRCUIT OPERATION
^ Each wheel speed detecting section is a kind of a pulse generator. It consists of the encoder (plate on which the north and south pole of magnet are arranged alternately) for detecting the wheel speed, which rotates at the same speed of the wheels, and the wheel speed sensor. This detecting section outputs the frequency pulse signals in proportion to the wheel speed.
^ The pulse signals generated by the wheel speed detecting section 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 signals from each wheel speed sensor while the vehicle is being driven. If any abnormality below is detected in the sensor signals, ASC-ECU sets the relevant diagnostic trouble code.
^ Irregular change in the wheel speed sensor signal
^ Wheel speed sensor signal continuously indicates higher value than the values of other wheel speed sensors.
PROBABLE CAUSES
Current trouble
^ Excessive gap between the wheel speed sensor and the magnetic encoder for wheel speed detection
^ Adhesion of foreign materials on the wheel speed sensor
^ Adhesion of foreign materials on the magnetic encoder for wheel speed detection
^ Wheel bearing malfunction
^ Malfunction of wheel speed sensor
^ Damaged wiring harness and connectors
^ External noise interference
^ Improper installation of the wheel speed sensor
^ Deformation of the magnetic encoder for wheel speed detection
^ ASC-ECU malfunction
^ Disturbance of magnetization pattern for magnetic encoder for wheel speed detection
^ The number of poles on the magnetic encoder for wheel speed detection (the number of N-pole and S-pole) is changed.
Past trouble
^ When DTC No. C102B is also set, perform the diagnosis with a particular emphasis on the wiring harness and connector failures between ASC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to Treat Past Trouble.
^ When the diagnostic trouble code No.C102B is not set, the following conditions may be present:
^ Wheel(s) spinning
^ Unstable vehicle attitude (spin)
^ External noise interference
^ Vehicle ran with the parking brake applied.
DIAGNOSIS
Required Special Tools:
^ MB991958 Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827 M.U.T.-III USB Cable
^ MB991910 M.U.T.-III Main Harness A
^ MB991997: ASC check harness
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines (Refer to CAN Bus Diagnostics Table Scan Tool Testing and Procedures). On completion, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1032 set?
YES: Go to Step 3.
NO: This diagnosis is complete.
STEP 3. Scan tool diagnostic trouble code
Check if DTC No. C102B is also set.
Q: Is DTC C102B also set?
YES: Carry out the diagnosis for DTC C102B. (Refer to C100A.)
NO: Go to Step 4.
STEP 4. Check of wheel speed sensor installation status
Check the installation status of wheel speed sensor [RR] (disconnection of wheel speed sensor, looseness of mounting bolt, etc.).
Q: Is the check result normal?
YES: Go to Step 5.
NO: Reinstall the wheel speed sensor [RR] correctly. Then go to Step 16.
STEP 5. Check of wheel speed sensor as a single unit
Q: Is the check result normal?
YES: Go to Step 6.
NO: Replace the wheel speed sensor [RR]. Then go to Step 16.
STEP 6. Wheel bearing looseness check
NOTE:
^ Wheel bearing looseness may increase the gap between the wheel speed sensor and the wheel speed detection magnet encoder.
^ Check the wheel bearing [RR] for looseness. (Refer to On-vehicle Service Testing and Inspection.)
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the rear wheel hub assembly.
STEP 7. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or deformation.
Q: Is the check result normal?
YES: Go to Step 8.
NO (Adhesion of foreign materials): Clean the encoder so as not to disturb the magnetization pattern on the encoder while taking care of the magnet, magnetic substance, and magnetic attraction. Then go to Step 16.
NO (Deformation): Replace the rear wheel hub assembly. Then go to Step 16.
STEP 8. Voltage measurement at A-05 ASC-ECU connector
1) Disconnect the ASC-ECU connector, connect the special tool ASC check harness (MB991997) to the wiring harness-side connector, and then measure 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 circuit power supply terminal (signal terminal) No. 43 and the body ground as well as between the ground terminal No. 42 and the body ground.
OK: 1 volt or less
Q: Is the check result normal?
YES: Go to Step 9.
NO (Not normal at the terminal No. 43 or 42): Go to Step 10.
STEP 9. Resistance measurement at A-05 ASC-ECU connector
1) Disconnect the ASC-ECU connector, connect the special tool ASC check harness (MB991997) to the wiring harness-side connector, and then measure 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 circuit power supply terminal (signal terminal) No. 43 and the body ground as well as between the ground terminal No. 42 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 12.
NO (Not normal at the terminal No. 43 or 42): Go to Step 10.
STEP 10. Connector check: A-05 ASC-ECU connector, C-47 intermediate connector, D-09 wheel speed sensor [RR] connector
Q: Is the check result normal?
YES: Go to Step 11.
NO: Repair the defective connector. Then go to Step 16.
STEP 11. Wiring harness check between A-05 ASC-ECU connector terminal No. 43 and D-09 wheel speed sensor [RR] connector terminal No. 1, and between A-05 ASC-ECU connector terminal No. 42 and D-09 wheel speed sensor [RR] connector terminal No. 2
^ Check for short circuit in wheel speed sensor [RR] circuit
Q: Is the check result normal?
YES: Replace the wheel speed sensor [RR]. Then, go to Step 16.
NO: Repair the wiring harness. Then go to Step 16.
STEP 12. Voltage measurement at A-05 ASC-ECU connector
1) Disconnect the ASC-ECU connector, connect the special tool ASC check harness (MB991997) to the ASC-ECU-side connector and the wiring harness-side connector, and then measure at the special tool connector side.
2) Turn the ignition switch to the ON position.
3) Measure the voltage between the wheel speed sensor circuit power supply terminal (signal terminal) No. 43 and the body ground.
OK: Battery positive voltage
Q: Is the check result normal?
YES: Go to Step 13.
NO: Go to Step 15.
STEP 13. Connector check: A-05 ASC-ECU connector, C-47 intermediate connector, D-09 wheel speed sensor [RR] connector
Q: Is the check result normal?
YES: Go to Step 14.
NO: Repair the defective connector. Then go to Step 16.
STEP 14. Wiring harness check between A-05 ASC-ECU connector terminal No. 43 and D-09 wheel speed sensor [RR] connector terminal No. 1, and between A-05 ASC-ECU connector terminal No. 42 and D-09 wheel speed sensor [RR] connector terminal No. 2
^ Open circuit check of wheel speed sensor [RR] circuit
Q: Is the check result normal?
YES: Go to Step 15.
NO: Repair the wiring harness. Then go to Step 16.
STEP 15. Check whether the DTC is reset.
1) Erase the DTC.
2) Drive the vehicle at 12 mph (20 km/h) or more.
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 C1032 set?
YES: Replace the hydraulic unit (incorporates in ASC-ECU). Then go to Step 16.
NO: Intermittent malfunction.
STEP 16. Check whether the DTC is reset.
1) Erase the DTC.
2) Drive the vehicle at 12 mph (20 km/h) or more.
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 C1032 set?
YES: Return to Step 1.
NO: This diagnosis is complete.