Test DH Throttle Position Sensor

To prevent replacement of good components, check throttle stop adjustment, speed control linkage, wiring, wiring harness, connectors and other mechanically related components.

1. TPS Voltage Check: Install breakout box and turn ignition key to "ON" position. Using DVOM on 20-volt scale, measure voltage between pins No. 28 and 40, and pins No. 47 and 40 on vehicles built after 11/2/87. On all others, measure resistance between pins No. 24 and 40. With accelerator depressed, reading should be greater than 10 volts on pin No. 28 and less than 1.5 volts on pins No. 47 and 24. With accelerator released, reading should be less than 1.5 volts on pin No. 28 and greater than 10 volts on pins No. 47 and 24.
2. Signal Return Check: Turn ignition off and install breakout box. Using DVOM on 200-ohm scale, measure resistance between pin No. 46 and TPS Blue/Yellow wire, and pin No. 46 and chassis ground. If resistance is 5 ohms or more, repair open in wire(s) in question. If resistance is less than 5 ohms, proceed to next step.
3. TPS Operation Check: With ignition off and using DVOM on 200-ohm scale, on vehicles built after 11/2/87, measure resistance between Green/Orange and Blue/Yellow wires. With accelerator depressed, reading should be less than 5 ohms. With accelerator released, reading should be greater than 10,000 ohms. Measure resistance between Orange and Blue/Yellow wires. With accelerator depressed, reading should be greater than 10,000 ohms. With accelerator released, reading should be less than 5 ohms.
4. On vehicles built before 11/2/87, measure resistance between Light Green/Red and Blue/Yellow wires. With accelerator depressed, reading should be less than 5 ohms. With accelerator released, reading should be greater than 10,000 ohms. Measure resistance between Red/Green and Blue/Yellow wires. With accelerator depressed, reading should be greater than 10,000 ohms. With accelerator released, reading should be less than 5 ohms. If all resistances are within specification, replace ECA.

Fig 1: Throttle Position Sensor Circuit