Code 24, Vehicle Speed Sensor Circuit

The Vehicle Speed Sensor (VSS) is a reed switch located behind instrument panel. The ECM provides battery voltage to switch, which toggles the voltage high and low. This pulsed signal is used by ECM to determine vehicle speed (MPH or km/h).

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

Code 24 is set if vehicle speed equals 0 MPH under the following conditions:
- Engine speed is between 1500-4400 RPM.
- VSS indicates less than 3 MPH.
- No Code 33 stored in memory.
- MAP reads low voltage with high vacuum (low load condition).
- Gear is not in Park or Neutral.
- All conditions are met for 5 seconds.
These conditions are met during a road-load deceleration. Disregard Code 24 that is set when drive wheels are not turning.