Code 24, Vehicle Speed Sensor (VSS) Circuit: Notes

Vehicle Speed Sensor (VSS) is a magnetic reed switch located behind instrument panel. ECM provides battery voltage to switch, which toggles 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 will set if vehicle speed is zero MPH when:
- Engine is speed is 1500-4400 RPM.
- Vehicle speed is indicated at less than 3 MPH.
- Code 33 is not set.
- MAP sensor reading is less than 6.3 psi (43 kPa).
- Gear not in Park or Neutral (A/T only).
- All above condition 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.