ABS W/EBD System

DTC C1278/78 ABNORMAL CHANGE IN OUTPUT VOLTAGE OF LEFT REAR SPEED SENSOR (TEST MODE DTC)

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The speed sensor detects wheel speed and transmits the appropriate signals to the skid control ECU. These signals are used for control of the ABS control system. Each of the front and rear rotors has 48 serrations.

When the rotors rotate, the magnetic field generated by the permanent magnet in the speed sensor induces AC voltage. Since the frequency of this AC voltage changes in direct proportion to the speed of the rotor, the frequency is used by the skid control ECU to detect the speed of each wheel.

DTCs C1273/73, C1274/74, C1277/77 and C1277/78 are output only in the test mode (SIGNAL CHECK). During test mode (SIGNAL CHECK), the skid control ECU records DTCs, if the abnormal sensor signal is received.

HINT:
DTC No. C0210/33 and C1332/38 are for the rear speed sensor RH.
DTC No. C0215/34 and C1333/39 are for the rear speed sensor LH.

Wiring Diagram:

Step 1-2:

Step 3-4:

Step 5-6:

Step 7:

Step 8:

Step 9:

INSPECTION PROCEDURE

HINT: Start the inspection from step 1 when using the hand-held tester and start from step 2 when not using the hand-held tester.