P0503

DTC P0503 VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

DTC Detection Conditions:

Automatic Transaxle Models:
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.




Manual Transaxle Models:
Vehicles, which are equipped with manual transaxle, detect the vehicle speed using the No.1 vehicle speed sensor. The No.1 vehicle speed sensor transmits a 4-pulse signal for every revolution of the rotor shaft, which is rotated by the transaxle or transfer output shaft via the driven gear. The 4-pulse signal is converted into a more precise rectangular waveform by the waveform shaping circuit inside the combination meter. The signal is then transmitted to the ECM. 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. 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.