Cummins ISX11.9 CM2250 – Service Manual 019-267   Cab Switchable Governor Switch Circuit

Resistance Check

TOC

 CAUTION 

The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.

If INSITE™ electronic service tool is available, monitor the switch for proper operation. If
not, follow the following procedure.

Disconnect the original equipment manufacturer (OEM) harness connector from the electronic control module (ECM). Set the multimeter to measure resistance. Insert a test lead into the accelerator governor switch input pin of the OEM harness connector, and attach the alligator clip to a multimeter probe. Touch the other multimeter probe to engine block ground.

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Transition the switch from one position to the other and measure the resistance at both positions. The multimeter
must show a value of 100k ohms or more (open circuit) while the switch is in one position, and a value of 10 ohms or less (closed circuit) in the other position.

If the switch does
not transition from an open to a closed circuit when flipped from one position to the other, there is an open circuit in the input wire. If the specification is correct, the circuit
must still be checked for a short circuit to ground, a short circuit from pin-to-pin, and a short circuit to an external voltage source.

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Check for Short Circuit to Ground

TOC

 CAUTION 

The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.

Disconnect the OEM harness connector from the ECM. Set the multimeter to measure resistance.

Insert a test lead into the accelerator governor switch input pin of the OEM harness connector, and attach the alligator clip to a multimeter probe.

Touch the other multimeter probe to engine block ground. Move the switch from its present position to the other position, and measure the resistance.

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

If the multimeter does
not show an open circuit, there is a short circuit to ground in the circuit.

Repair or replace the OEM harness. Refer to Procedure
019-071.

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Check for Short Circuit from Pin to Pin

TOC

 CAUTION 

The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.

Disconnect the OEM harness connector from the ECM. Set the multimeter to measure resistance.

Insert a test lead into the accelerator governor switch input pin of the OEM harness connector, and attach the alligator clip to a multimeter probe.

Touch the other multimeter probe with attached test lead to all other pins in the connector. Measure the resistance.

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The multimeter
must show a value of 100k ohms or more (open circuit) at all pins.

If any circuit is
not open, there is a short circuit between the input pin and the applicable pin.

Repair or replace the OEM harness. Refer to Procedure
019-071.

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Check for Short Circuit to External Voltage Source

TOC

 CAUTION 

The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.

Disconnect the OEM harness connector from the ECM. Set the multimeter to measure VDC. Turn the keyswitch to the ON position.

Insert a test lead into the accelerator governor switch input pin of the OEM harness connector, and attach the alligator clip to a multimeter probe.

Touch the other multimeter probe to engine block ground and measure the voltage.

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The multimeter
must show a value of 1.5 VDC or less.

If the voltage is more than 1.5 VDC, there is a short circuit to an external voltage source.

Remove the external voltage source.

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Last Modified:  30-May-2008