DTC 21

DTC 21 VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

DTC Detection Condition:

Vehicles, which are equipped with ABS (Anti Lock Brake System), detect the vehicle speed using the skid control ECU and wheel speed sensor. The wheel speed sensor monitors the wheel rotation speed and sends a signal to the skid control ECU. The skid control ECU converts the wheel speed signal into a 4 pulse signal and transmits it to the ECM via the combination meter. The ECM determines the vehicle speed based on the frequency of the pulse signal.

Wiring Diagram:

Step 1:

Step 2:

INSPECTION PROCEDURE

HINT: Read freeze frame data using a hand held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data, from the time the malfunction occurred.