Vehicle Speed Sensor Circuit Test

OPERATION
- The vehicle speed sensor is directly attached to the speedometer driven gear in the transmission. It detects the vehicle speed and sends it to the engine control module after converting to pulse signals, based on which the engine control module controls the idle speed control motor.
- The output terminal of the vehicle speed sensor has a voltage of approx. 5 V applied from the control module. The vehicle speed sensor generates pulse signals by turning on and oft the power transistor.

TROUBLESHOOTING HINTS
If there is an open or short circuit in the vehicle speed sensor signal circuit, the engine may stall when the vehicle is decelerated to stop.

HARNESS INSPECTION





Measure the line voltage of the vehicle speed sensor.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): Battery positive voltage
OK: GO TO STEP 2
NG: Repair the harness. (A1 - Ignition switch)





Check the vehicle speed sensor output circuit for continuity.
- Engine control module connector: Disconnected
- Ignition switch: ON
- Move the vehicle
Continuity: Continuity and no-continuity are repeated alternately
OK: STOP
NG: GO TO STEP 3





Measure the power supply voltage of the vehicle speed sensor.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): 4.5 - 4.9
OK: GO TO STEP 4
NG: Repair the harness. (A3-80)





Check for continuity of the ground circuit.
- Connector: Disconnected
OK: STOP
NG: Repair the harness. (A2 - Ground)