Speedometer Module: Description and Operation

Power for the speedometer is supplied on circuit G5. This circuit is spliced and supplies power to all the gauges. Ground for the speedometer is provided on circuit Z1. This circuit is spliced and supplies ground for the tachometer, engine oil pressure gauge, engine coolant temperature gauge, and the voltmeter.

The speedometer is an electro-mechanical design. The speedometer pointer movement is controlled by the output of an integrated circuit board assembly which is mounted on the speedometer circuit board assembly.

The vehicle speed signal, sent to the speedometer, is an output of the Vehicle Speed Sensor (VSS) on circuit G7. The G7 circuit connects from the VSS to the Ignition Control Module (ICM) cavity 24. The ICM processes this signal and sends it to the Powertrain Control Module (PCM) on the MUX line. This is the D37 circuit which connects to cavity 15 of the ICM and to cavity 37 of the PCM.

The PCM processes the VSS signal and sends a signal to the speedometer on circuit G17.

The G17 circuit is double crimped at the bulkhead connector and supplies an input back to the ICM.