Tires of Different Size - Vehicle Stability Control System (for BOSCH Made)

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM (for BOSCH Made): C1237/37: Tires of Different Size
C1237/37 - Tires of Different Size

DESCRIPTION

The skid control ECU measures the speed of each wheel by receiving signals from the speed sensor.

These signals are used for recognizing that all 4 wheels are operating properly.

Therefore, all wheel signals must be equal.





WIRING DIAGRAM









INSPECTION PROCEDURE

HINT
Check the condition of each related circuit connector before troubleshooting Electronic Circuit Inspection Procedure.

PROCEDURE

1. CHECK TIRES

(a) Check the size and condition of all 4 wheels Component Tests and General Diagnostics.

HINT
The DTC is output when tire deformation or a difference in tire size is detected.

OK:

The diameter of all 4 tires and air pressure are the same.

NG -- REPLACE TIRES SO THAT ALL 4 TIRES ARE THE SAME SIZE
OK -- Continue to next step.

2. INSPECT SPEED SENSOR AND SENSOR ROTOR SERRATIONS

(a) Lift up the vehicle.





(b) Disconnect the skid control ECU connector.

(c) Connect the oscilloscope to each speed sensor terminal of the skid control ECU connector.

Terminals:





(d) Check that a waveform is output when the tires are rotated (by the sensor circuit).





OK:

A waveform as shown in the figure is output.

HINT
* Each sensor circuit outputs the same waveform without noise.
* As vehicle speed (wheel rotation speed) increases, the width of the waveform narrows and the fluctuation in the output voltage becomes greater.
* When noise is identified in the waveform on the oscilloscope, the erratic signals are generated due to rotor scratches, looseness or foreign matter attached to the speed sensor.

(e) Make sure that the waveform does not change while jiggling a connector or a wire harness.

OK:

The waveform does not change.

HINT
If the waveform changes while jiggling a connector or a wire harness, there may be a malfunction in the connector or the wire harness.

(f) Connect the connector.

NG -- CHECK SPEED SENSOR ROTOR
OK -- Continue to next step.

3. RECONFIRM DTC

(a) Clear the DTC Vehicle Stability Control System (for BOSCH Made).

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 mph (32 km/h) or more for 60 seconds or more.

(d) Check if the same DTC is recorded Vehicle Stability Control System (for BOSCH Made).

HINT
Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result:





B -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System

4. CHECK SPEED SENSOR ROTOR

(a) Check the speed sensor rotor.

Front Speed Sensor Rotor (Front drive outboard joint shaft assembly): Components

Rear Speed Sensor Rotor (Rear axle hub and bearing assembly): Components

OK:

No scratches or foreign matter on the rotors.

NOTICE:
Check the speed sensor signal after the cleaning/replacement Test Mode Procedure.

NG -- CLEAN OR REPLACE SPEED SENSOR ROTOR
OK -- Continue to next step.

5. CHECK SPEED SENSOR TIP

(a) Remove each speed sensor Removal for front, Removal for rear).

(b) Check the speed sensor tip.

OK:

No scratches or foreign matter on the sensor tip.

NOTICE:
Check the speed sensor signal after the cleaning/replacement Test Mode Procedure.

(c) Install the speed sensor.

NG -- CLEAN OR REPLACE SPEED SENSOR
OK -- Continue to next step.

6. INSPECT SPEED SENSOR

(a) Disconnect each speed sensor connector.





(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:

FRONT
REAR










NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

NG -- REPLACE SPEED SENSOR
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU TO SPEED SENSOR)

(a) Disconnect the skid control ECU connector.





(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:

FRONT
REAR










(c) Connect the connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (SKID CONTROL ECU TO SPEED SENSOR)
OK -- Continue to next step.

8. RECONFIRM DTC

(a) Clear the DTC Vehicle Stability Control System (for BOSCH Made).

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 mph (32 km/h) or more for at least 60 seconds.

(d) Check if the same DTC is recorded Vehicle Stability Control System (for BOSCH Made).

HINT
Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result:





B -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System