| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Circuit Description
Vehicle Speed Sensor (VSS), driven by speedometer cable, outputs a signal from instrument cluster to ECM. Instrument cluster converts signal to a more precise waveform for ECM. DTC is set when ECM does not detect any signal while vehicle is in motion. Possible causes are
- Instrument cluster.
- Speed sensor open or short circuit.
- ECM.
- Speedometer cable.