1975-76 Models

Check sensor terminals at back of speedometer for proper connections. Block front wheels and jack up one rear wheel off ground. Release parking brake and place transmission in Neutral.
Unplug wiring connector from computer. Using a 10 ohm resistor, connect positive lead of ohmmeter to computer connector speed sensor terminal. See Fig 1. Connect negative ohmmeter lead to a known good ground.
Have an assistant turn rear wheel slowly and observe voltmeter. Ohmmeter should fluctuate near infinity mark. If not, replace speedometer assembly if wiring is not defective.

Fig 1: 1975-76 Speed Sensor Test
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Fig 2: 1975 Transmission Controlled Spark System Test (Calif. 2T-C Engine)

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Fig 3: 1975-76 Transmission Controlled Spark System Test (2F Engine)

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Fig 4: 1975-76 Transmission Controlled Spark System (4M Engine)

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Fig 5: 1976 Transmission Controlled Spark System Test (Calif. 2T-C Engine)

Fig 6: 1976 Transmission Controlled Spark System Test (20R Engine)