Code 24, Vehicle Speed Sensor 2.5L TBI - A Body (With In-Dash Speed Sensor): Notes

The ECM applies and monitors a 12-volt signal on circuit No. 437. Circuit No. 437 connects to the vehicle speed sensor and is alternately grounded when the wheels are turning. The pulsing action takes place approximately 2000 times per mile and the ECM will calculate vehicle speed based on the time between pulses.

Code 24 will set if vehicle speed reads zero MPH, transmission is not in Park or Neutral, engine speed is between 1400-4400 RPM, TPS is less than 2 percent, a high manifold vacuum is sensed by the MAP sensor, and these conditions have existed for more than 5 seconds.

1. ECM monitors circuit No. 437, counting voltage pulses created by the grounding of the speed sensor. "Scan" reading should closely match speedometer reading with drive wheels turning.
2. 8-12 volts at the I. P. connector indicates circuit No.437 is open or there is a faulty speed sensor. A voltage of less than one volt at I. P. connector indicates that circuit No. 437 wire is shorted to ground or open between the connector and the ECM. The I.P. connector is located in the center console near the ECM.