Service manual

90-898303

4-20

DDT TEST

The TPS settings are not adjustable, but can be monitored with the Digital

Diagnostic Terminal (DDT). Voltage change should be smooth from idle to

wide open throttle. If voltage change is erratic, the TPS is defective.

1. Set the DDT’s data monitor to read TPS voltage. Refer to the Digital

Diagnostic Terminal Technician Reference Manual for instructions.

NOTE: Refer to appropriate service manual for test procedure and

specifications.

2. If the throttle position sensor(s) are out of the intended operating range

when the engine is started, the PCM senses that the TPS has failed. The

warning horn sounds, the CHECK ENGINE light illuminates, the DDT

indicates a failed TPS, and the engine goes into rpm reduction.

3. Visually inspect the sensor.

RESISTANCE TEST

1. Remove the linkage connected to the TPS.

2. Remove the TPS from the engine and the harness.

3. Connect an Ohmmeter between the PPL/YEL and BLK/ORN leads on the

sensor.

Reading:

Approximately 2500 Ω <± 375 Ω)

4. Connect an Ohmmeter between the PPL/YEL and LT BLU/WHT leads on

the sensor.

5. Slowly rotate the sensor mechanism from idle position through WOT and

observe the reading. Resistance change should be smooth from idle to wide

open throttle. If resistance change is erratic, replace the TPS.

6. Connect an Ohmmeter between the BLK/ORN and LT BLU/WHT leads on

the sensor.

7. Slowly rotate the sensor mechanism from WOT to idle position and observe

the reading. Resistance change should be smooth from idle to wide open

throttle. If resistance change is erratic, replace the TPS.

Notes

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