Code 24, Vehicle Speed Sensor Circuit

ECM supplies a B+ signal to Vehicle Speed Sensor (VSS). While vehicle is moving, a reed switch inside VSS will open and close, toggling B+ signal high and low.

1. If speedometer is inoperative, this could cause Code 24.
2. Checks if ECM is supplying B+ to VSS.
3. The VSS on the back of instrument panel will toggle B+ signal high and low. Code 24 will set under the following conditions: fuel is cut for 4 seconds or longer, engine speed is less than 4000 RPM, and vehicle speed is less than one MPH.