CM850 Electronic Control System – 019-375   EGR Valve Assembly Circuit

Disconnect the EGR valve motor connector from the engine harness. Disconnect the 60-pin engine harness connector from the ECM.

Check the EGR valve motor connector and engine harness connectors for broken, bare, or melted wires; loose, dirty, damaged, or missing pins; and other visible signs of damage.

CAUTION  To reduce the possibility of pin and connector damage, use test leads, Part Numbers 3822758 and 3823993, when taking a measurement.

Disconnect the 60-pin engine harness connector from the ECM. Disconnect the EGR valve motor from the engine harness. Set the multimeter to measure resistance.

Insert a test lead into the EGR valve motor signal pin of the 60-pin engine harness connector. Connect the alligator clip to a multimeter probe. Insert the second test lead to the signal pin of the EGR valve motor harness connector and connect the clip to the other multimeter probe. Measure the resistance.

The multimeter must show a measurement of 10 ohms or less
(closed circuit).

If the measured value is more than 10 ohms, there is an open circuit in the signal wire.

Repair or replace the engine harness. Refer to Procedure 019-043.

Repeat the resistance check for the return wire. Measure the resistance from the EGR valve motor return pin of the 60-pin engine harness connector to the EGR valve motor return pin of the harness connector.

The multimeter must show a measurement of 10 ohms or less
(closed circuit).

If the measured value is more than 10 ohms, there is an open circuit in the return wire.

Repair or replace the engine harness. Refer to Procedure 019-043.

CAUTION  To reduce the possibility of pin and connector damage, use test lead, Part Number 3822758, when taking a measurement.

Disconnect the 60-pin engine harness connector from the ECM. Disconnect the EGR valve motor from the engine harness. Set the multimeter to measure resistance.

Insert the test lead into the EGR valve motor signal pin of the 60-pin engine harness connector. Touch the other multimeter probe to engine block ground. Measure the resistance.

The multimeter must show a measurement of 100k ohms or more (open circuit).

If the measured value is less than 100k ohms, there is a short circuit to ground in the signal wire.

Repair or replace the engine harness. Refer to Procedure 019-043.

Repeat the short-to-ground check for the return wire. Measure the resistance from the EGR valve motor return pin of the 60-pin engine harness connector to engine block ground.

The multimeter must show a measurement of 100k ohms or more (open circuit).

If the measured value is less than 100k ohms, there is a short circuit to ground in the return wire.

Repair or replace the engine harness. Refer to Procedure 019-043.

Disconnect the 60-pin engine harness connector from the ECM. Disconnect the EGR valve motor from the engine harness. Set the multimeter to measure resistance.

Measure the resistance from the EGR valve motor signal pin in the 60-pin engine harness connector to all other pins in the connector.

The multimeter must show a measurement of 100k ohms or more (open circuit).

If the measured value is less than 100k ohms, there is a short circuit between the signal wire and any other pin that measured a closed circuit.

Repair or replace the engine harness. Refer to Procedure 019-043.

Disconnect the 60-pin engine harness connector from the ECM. Disconnect the EGR valve motor from the engine harness. Set the multimeter to measure VDC. Turn the vehicle keyswitch to the ON position.

Insert the test lead connected to the positive (+) multimeter probe into the EGR valve motor signal pin of the 60-pin engine harness connector. Touch the negative (-) multimeter probe to engine block ground and measure the voltage.

If voltage is present, there is a short circuit from the signal wire to an external voltage source.

Remove the external voltage source.

Repeat the short-to-external-voltage-source check for the return wire. Measure the voltage from the EGR valve motor return pin of the 60-pin engine harness connector to engine block ground.

If voltage is present, there is a short circuit from the return wire to an external voltage source.

Remove the external voltage source.