Code 24 - Vehicle Speed Sensor: Notes

The ECM monitors the output from the Permanent Magnet (PM) generator mounted in the transaxle on circuits No. 400 and 401. The PM generator produces a pulsating, alternating current whenever vehicle speed is greater than 3 MPH. The AC voltage level and the number of pulses increases with vehicle speed. The ECM will calculate vehicle speed based on the time between pulses. The VSS buffer used on other models is incorporated into the ECM on these models.

If the vehicle is equipped with a digital speedometer and odometer and/or cruise control. The ECM provides pulses for operation of these components (2000 and 4000 pulses per mile respectively). The "Scan" tester reading should closely match speedometer reading when drive wheels are turning.

1. Code 24 will set if vehicle speed equals zero MPH when engine speed is between 1400 and 3600 RPM, throttle opening is less than 2 percent, a low load condition exists and transmission is not in Park or Neutral. All conditions must be met for 4-5 seconds during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning.