Engine Control System

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

CIRCUIT DESCRIPTION

DTC Detection Condition:

The vehicle speed sensor detects the rotation speed of the transmission output shaft and sends signals to the ECM. The ECM determines the vehicle speed based on these signals. An AC voltage is generated in the vehicle speed sensor coil when the rotor mounted on the output shaft rotates, and then this voltage is sent to the ECM.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

The ECM assumes that the vehicle is driven when the RPM of the transmission counter gear indicates more than 300 rpm and it has been over 30 sec. since the park/neutral position switch was turned OFF. If there is no signal from the vehicle speed sensor when these conditions are satisfied, the ECM concludes that there is a fault in the vehicle speed sensor. The ECM will turn on the MIL and a DTC is set.

Wiring Diagram:

Step 1:

Step 2 - 3:

Step 4:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.

CHECK FOR INTERMITTENT PROBLEMS

Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.

a. Clear the DTCs.
b. Set the check mode.
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.