019-049   Fuel Shutoff Valve Circuit

The fuel shutoff solenoid valve (4) is mounted on top of the fuel pump on the engine. The solenoid is controlled by the ECM.

NOTE: Only one wire from the ECM will be attached to the solenoid post. The ECM is

not capable of supplying power for other auxiliary components. If an external voltage source is attached, a fault code will be induced.

The solenoid will open when the ECM senses the keyswitch is ON. The solenoid will close when the ECM senses the keyswitch is OFF or when the ECM senses an engine overspeed.

For more information on the fuel shutoff valve, refer to Procedure

005-043 in the Troubleshooting and Repair Manual, N14 Engine, Bulletin

3666142, or the Troubleshooting and Repair Manual, M11 Engine, Bulletin

3666139.

The fuel shutoff valve circuit is a signal wire, pin 16, of the actuator harness to the shutoff valve solenoid. The valve is grounded through the engine. Disconnect the actuator harness connector from the ECM. Check for damaged pins. Refer to Procedure

019-043. Disconnect the fuel shutoff solenoid wire from the valve post.

CAUTION  To reduce the possibility of connector damage, do not use probes or leads other than Part Number 3822758. The leads must fit tightly in the connector without expanding the pins in the connector.

Insert a test lead into pin 16 of the actuator harness connector. Connect the alligator clip to the multimeter probe.

Touch the other multimeter probe to the fuel shutoff valve solenoid wire. Measure the resistance. The multimeter

must show a closed circuit (10 ohms or less). If the circuit is

not closed, repair or replace the actuator harness. Refer to Procedure

019-043. If the circuit is closed, it

must
still be checked for a short to ground and short from pin to pin.

Insert a test lead into pin 16. Attach it to the positive (+) multimeter probe. Touch the other multimeter probe to the engine block ground. The ring terminal at the solenoid

must be disconnected and can

not touch anything that is grounded. Measure the resistance. The multimeter

must show an open circuit (more than 100k ohms). If the circuit is

not open, there is a short to ground in the wire connected to pin 16. Repair or replace the actuator harness. Refer to Procedure

019-043.

Check for a short circuit from pin 16 to all of the other pins in the actuator harness connector. Connect the alligator clip to the other multimeter probe. Insert test lead into all of the other pins in the actuator.

The ring terminal at the solenoid

must be disconnected and can

not touch anything that is grounded. The battery voltage supply

must be disconnected.

Measure the resistance. The multimeter

must show an open circuit (more than 100k ohms). If the circuit is

not open, there is a short between pin 16 and any pin that measured a closed circuit. Repair or replace the actuator harness. Refer to Procedure

019-043.

Check for a short circuit from the fuel shutoff valve circuit to a +12-VDC source. Connect the battery voltage supply if it has been disconnected. Turn keyswitch ON. Adjust the multimeter to measure DC voltage. Insert a test lead into pin 16. Touch the other multimeter probe to the engine block ground.

NOTE: An external voltage source is

any wire in the OEM wiring that carries voltage.

Measure the voltage. The voltage

must be 1.5 VDC or less. If the voltage is

not correct, there is a short circuit between the fuel shutoff valve circuit and an external voltage source. Remove the external voltage source.

Connect all components after the repair is complete.