Vehicle Speed Sensor: Testing and Inspection

Fig. 48 Checking vehicle speed sensor. 1987 - 88 models:

Circuit Test
1. Disconnect battery ground cable, then the ECM electrical connectors.
2. Connect a suitable ohmmeter between terminal 17 and ground, Fig. 48.
3. Raise and support vehicle, then simultaneously rotate both front wheels. Resistance should fluctuate between ``0'' and infinite ohms when both right and left wheels are rotated simultaneously.
4. If ohmmeter reading is not as specified, check for open or disconnected connector between terminal 17 and vehicle speed sensor.
5. Lower vehicle, then connect ECM electrical connector.
6. Connect battery ground cable.



Sensor Test
1. Disconnect battery ground cable, then the ECM electrical connector.
2. Remove instrument cluster bezel, then separate instrument cluster assembly from instrument panel.
3. Remove speedometer, then connect a suitable ohmmeter to 2 terminals of speed sensor, located on back of speedometer. Ohmmeter should indicate zero or infinite ohms.
4. Rotate speedometer cable one full turn clockwise and note that ohmmeter deflects toward open or closed 4 times. If faulty, replace speedometer.
5. Connect ECM electrical connector, then the battery ground cable.