Service manual

90-898303

4-21

VISUAL INSPECTION

If the DDT determines that the TPS sensor has failed, follow this procedure to

determine cause:

1. Disconnect the sensor from the harness connection.

2. Visually inspect the pins at the sensor and the wires coming from the

connector. Look for broken, bent, or corroded pins at the sensor and loose,

broken, or corroded wires at the connector. Replace components as

necessary.

3. Check the throttle cable adjustment. The throttle stop screw on the throttle

arm must be against the throttle stop on the cylinder block when the engine is

started. Pre-load the throttle cable barrel 1 or 2 turns if necessary.

4. Verify that the driver is not pushing on the throttle (if a foot throttle is used)

or advancing the throttle only on the control box.

5. Check the throttle cam-to-roller adjustment. If the roller is not down in the

pocket/ valley area on the cam, the roller has a tendency to ride up or down

on the cam, causing the TPS link arm to push/pull on the TPS lever. This

results in changing values.

6. Heat or pressure-test the TPS.

SENSOR HEAT TEST

IMPORTANT: Excessive heat damages the TPS.

1. With the engine at idle, heat the TPS with a hot air gun below the electrical

connection until the sensor is warm to the touch.

2. Watch for any of the following symptoms:

• RPM change

• CHECK ENGINE light illumination

• Momentary warning horn signal

• TPS voltage value change (0.5 volt) on DDT

Notes

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