Engine Control System - SFI System

2TR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0500: Vehicle Speed Sensor "A"

DTC P0500 - Vehicle Speed Sensor "A"

DTC P0503 - Vehicle Speed Sensor "A" Intermittent / Erratic / High

DESCRIPTION

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

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 2000 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.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





With Manual Transmission:





With Automatic Transmission:





TYPICAL MALFUNCTION THRESHOLDS





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT: Read freeze frame data using the Techstream. Freeze frame data records 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.

PROCEDURE

1. CHECK OPERATION OF SPEEDOMETER
(a) Drive the vehicle and check if the operation of the speedometer in the combination meter is normal.

HINT: The vehicle speed sensor is operating normally if the speedometer reading is normal.

NG -- CHECK SPEEDOMETER CIRCUIT
OK -- Continue to next step.
2. INSPECT ECM (SPD VOLTAGE)





(a) Move the shift lever to the neutral position.
(b) Jack up the vehicle.
(c) Turn the ignition switch to ON.
(d) Check the voltage between the terminals of the ECM connectors as the wheel is turned slowly.
Standard Voltage:





HINT: The output voltage should fluctuate up and down similarly to the diagram on the left when the wheel is turned slowly.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM