Code 24, Vehicle Speed Sensor Circuit: Notes

The Vehicle Speed Sensor (VSS) is a reed switch, located behind instrument panel. The ECM provides battery voltage to switch which toggles the voltage on and off. This pulsed signal is used by the ECM to determine MPH/KPH.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Code 24 sets if vehicle speed equals 0 MPH when:
- Engine speed is between 1800-4400 RPM.
- TPS is at zero percent (closed throttle).
- MAP reads low voltage with high vacuum (low load condition).
- Not in Park or Neutral.
- All conditions are met for 3 seconds.

These conditions are met during a road-load deceleration. Disregard Code 24 that sets when drive wheels are not turning.