Cruise Control System

DTC P0500 Vehicle Speed Sensor Circuit Malfunction
DTC P0503 Vehicle Speed Sensor Circuit Malfunction

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.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions (Part 1):

Typical Enabling Conditions (Part 2):

Typical Malfunction Thresholds:

Automatic Transaxle Models:
The ECM assumes that the vehicle is being driven, while the vehicle speed sensor signal is being transmitted by the combination meter. If there is no signal from the combination meter, despite the ECM detecting the speed signal from the No. 2 speed sensor, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and sets the DTC.

Manual Transaxle Models:
The ECM assumes that the vehicle is being driven, when the indicated engine speed is more than 2,000 rpm and the engine load calculated by the ECM is more than certain level. If there is no signal from the vehicle speed sensor, despite these conditions being met, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and sets the DTC.

Wiring Diagram:

INSPECTION PROCEDURE

HINT: Read freeze frame data using an intelligent 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.