Code No.C1210: Wheel speed sensor (RR) system (open 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 ).
Before replacing the ECU, ensure that the communication circuit is normal.
OPERATION
A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each wheel speed sensor.
The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the wheel speed sensor, and by the speed of rotation.
The wheel speed sensors transmit the frequency of the voltage pulses and the amount of voltage generated by each pulse to the ASTC-ECU.
The hydraulic unit assembly (integrated with ASTC-ECU) modulates the amount of braking force individually applied to each wheel cylinder.
DIAGNOSIS CODE SET CONDITIONS
Diagnosis code No.C1210 is set when signal is not input due to breakage of the wires of the four wheel speed sensors.
PROBABLE CAUSES
Current trouble
Damaged wiring harness and connectors
Wheel speed sensor malfunction
ASTC-ECU malfunction
Past trouble
Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASTC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Cope with Intermittent Malfunction ).
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnosis
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
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.
(1)Disconnect the F-10 rear wheel speed sensor (RH) connector, and measure the resistance at the F-10 rear wheel speed sensor (RH) side. (2)Measure the resistance between the F-10 rear wheel speed sensor (RH) connector terminal No.1 and No.2. OK: 0.9 - 1.3 kΩ
Q.
Is the check result normal?
Repair the harness wire between F-10 rear wheel speed sensor (RH) connector terminal No.1 and A-48 ASTC-ECU connector terminal No.28, or between F-10 rear wheel speed sensor (RH) connector terminal No.2 and A-48 ASTC-ECU connector terminal No.12. Then go to Step 8.
Replace the rear wheel speed sensor (RH) (Refer to ). Then go to Step 8.
STEP 7. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.
Q.
Is the diagnosis code No.C1210 set?
Replace the hydraulic unit (integrated with ASTC-ECU) (Refer to ). Then go to Step 8.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
STEP 8. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 15 km/h or more.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 15 km/h or higher.
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Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics table 
). On completion, go to Step 2.)
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