Carbureted Pickup

Jack up and support one rear wheel off ground. Release parking brake. Place shift lever in neutral position.
Unplug wiring connector from computer. Computer is located on left side of cowl on Pickup.
Test "ON-OFF" cycles of speed sensor using an ohmmeter. See Fig 1. Insert a 10 ohm resistor in series with positive ohmmeter lead and insert lead in rear of connector. Connect negative terminal to ground.
Turn wheel slowly, checking to see that ohmmeter needle deflects consistently. If ohmmeter needle does not deflect, check that sensor leads are firmly connected to rear of speedometer. If connections are okay, replace speedometer assembly.

Fig 1: Testing Speed Sensor (Pickup - Carbureted Models) Insert positive lead in rear of connector.