Mechanical Gas Fuel System G5.9, G8.3, G855 – Master Repair Manual 019-038   Engine Position Sensor (EPS)

General Information

TOC

The engine position sensor sends a reset signal to the ignition module to restart the cylinder firing sequence.

 
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Remove

TOC

NOTE: Shown throughout this procedure are the QSV81 and QSV91 graphics. Although this is a different engine, the procedure remains the same. See the Engine Diagrams in Procedure 100-002for the component location.

Disconnect the engine position sensor connectors from the engine harness.

Loosen the locknut.

Remove the engine position sensor from the flywheel housing.

This applies to both sensors.

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Inspect for Reuse

TOC

Inspect the engine position sensor for debris, cracked potting, chipped potting, extruded potting, and damage from contact with the flywheel.

If there is debris on the engine position sensor, clean the sensor.

If the sensor potting is chipped, cracked, or extruded, or if the sensor has been damaged by contact with the flywheel, replace the sensor with a new one.

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Install

TOC

When installing the engine position sensor, make sure the target is aligned with the pin on the flywheel housing.

Install the sensor into the hole until it touches the target.

NOTE: If the sensor does not turn in with finger pressure, check the flywheel housing hole threads and sensor threads for damage.

Turn the engine position sensor counterclockwise 2 turns.

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Tighten the locknut against the flywheel housing.

Torque Value:  27  n.m  [20 ft-lb]

NOTE: Overtightening the locknut can damage the sensor.

Connect the sensor to the sensor harness. Push the connectors together until they lock.

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Resistance Check

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Disconnect the engine position sensor connectors from the engine harness.

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Measure the resistance from pin to pin for each coil. The multimeter must measure between 700 and 2000 ohms. If both resistance values are within specifications, the sensor must still be checked for a short to ground.

If any of the preceding checks fail, replace the engine position sensor.

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Check for Short Circuit to Ground

TOC

Measure the resistance from both pins on each connector to the engine block. The multimeter must show an open circuit (100k ohms or more).

If either connector fails the test, replace the engine position sensor.

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Check for Short Circuit from Pin to Pin

TOC

Measure the resistance from pin to pin for each coil. The multimeter must show an open circuit (100k ohms or more).

If either connector fails the test, replace the engine position sensor.

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Last Modified:  10-Jul-2006