Code 42, Vehicle Speed Sensor Circuit: Notes

The ECM provides a 12-volt signal to the Vehicle Speed Sensor (VSS). The VSS will toggle the signal low and high indicating vehicle is moving. Code 42 sets if signal line stays high or low for 4 seconds or more.

1. If speedometer is inoperative, it could be the cause of Code 42.
2. The ECM supplies 12 volts to the VSS.
3. The VSS on the back of the instrument panel will toggle the 12 volts supplies by the ECM.