BR–88 BRAKE SYSTEM – ANTI–LOCK BRAKE SYSTEM (ABS) DTC 31 32 33 34 35 36 Speed Sensor Circuit CIRCUIT DESCRIPTION The speed sensor detects the wheel speed and sends the ap- propriate signals to the ECU. These signals are used to control both the ABS and TRAC control systems. The front and rear ro- tors each have 48 serrations. When the rotors rotate, the mag- netic field emitted by the permanent magnet in the speed sensor generates an AC voltage. Since the frequency of this AC volt- age changes in the direct proportion to the speed of the rotor, the frequency is used by the ECU to detect the speed of each wheel. Rotor Speed Sensor N S Magnet Coil To ECU High Speed Low Speed +V 0 -V BR3583 BR3582 DTC No. Diagnostic Trouble Code Detecting Condition Trouble area 31, 32 33, 34 Detection of any of conditions (1) through (3): (1) At vehicle speed of 10 km/h (6 mph) or more, pulses are not input for 5 sec. (2) Momentary interruption of he vehicle speed sensor signal occurs at least 7 times in the time between switching the ignition switch ON and switching it OFF. (3) Abnormal fluctuation of speed sensor sig- nals with the vehicle speed 20 km/H (12 mph) or more. Right front, left front, right rear and left rear speed sensor. Open or short in each speed sensor circuit. ECU 35 Speed sensor signal is not input for about 1 sec. while the left front and right rear speed sensor signals are being checked with the IG switch ON. Open in left front, right rear speed sensor circuit. ECU 36 Speed sensor signal is not input for about 1 sec. while the right front and left rear speed sensor signals are being checked with the IG switch ON. Open in right front, left rear speed sensor circuit. ECU HINT: DTC No.31 is for the right front speed sensor. DTC No. 32 is for the left front speed sensor. DTC No.33 is for the right rear speed sensor. DTC No.34 is for the left rear speed sensor. Fail safe function: If trouble occurs in the speed sensor circuit, the ECU cuts off current to the ABS solenoid relay and prohibits ABS control.