019-022   Cruise Control or PTO ON/OFF 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 circuit for proper operation. If
not, follow the troubleshooting procedures in this section.

 
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Disconnect the original equipment manufacturer (OEM) harness connector from the electronic control module (ECM).

Insert the test lead into the cruise control ON/OFF switch signal pin of the original equipment manufacturer (OEM) harness connector and attach it to the multimeter probe. Touch the other probe to the engine block ground.

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Move the ON/OFF switch to the ON position. The multimeter
must show a closed circuit (10 ohms or less). If the circuit is
not closed, inspect the cruise control ON/OFF switch input for an open circuit. Refer to the OEM troubleshooting and repair manual.

If the resistance is within specification, the cruise control ON/OFF switch input
must be checked for a short circuit to ground, a short circuit from terminal to terminal, and a short circuit to an external voltage source.

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Check for Short Circuit to Ground

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To isolate the cruise control circuit when checking for a short circuit, disconnect the OEM harness connector from the ECM and the OEM harness from the cruise control switch.

Disconnect the clutch pedal position switch, idle validation on/off switch, and the accelerator pedal position switch. Set all cab panel switches to the OFF or neutral position.

Set the service brake using the trailer brake hand valve.

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Adjust the multimeter to measure resistance. Insert a test lead into the cruise control ON/OFF switch input of the OEM harness connector and attach it to a multimeter probe. Remove the other multimeter probe from the alligator clip and touch it to the engine block ground.

Measure the resistance.

The multimeter
must show an open circuit (100k ohms or more). If the circuit is
not open, there is a short circuit to ground in the cruise control circuit, provided that the switch has been previously checked.

Repair or replace the wire connected to the cruise control ON/OFF switch input in the OEM harness according to the vehicle manufacturer’s procedures.

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Check for Short Circuit from Pin to Pin

TOC

Check for a short circuit from pin-to-pin. Isolate the cruise control circuit by setting the switches as in the previous section. Set the cruise control/PTO ON/OFF switch to the OFF position. Insert the lead into the cruise control ON/OFF switch input. Connect the alligator clip to the multimeter. With the other lead inserted into the switch return wire(s), measure the resistance.

The multimeter
must show an open circuit (100k ohms or more).

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Remove the lead from the cruise control ON/OFF switch input and check all other pins. Measure the resistance. The multimeter
must show an open circuit (100k ohms or more).

If the circuit is
not open, there is a short circuit between the cruise control ON/OFF switch input circuit and any pin that shows a closed circuit, provided the switch has previously been checked.

Repair or replace the wires in the OEM harness according to the vehicle manufacturer’s procedures.

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Check for Short Circuit to External Voltage Source

TOC

Turn the vehicle keyswitch to the ON position. Set the cruise control/PTO ON/OFF switch to ON. Adjust the multimeter to measure VDC. Insert a test lead into the cruise control ON/OFF switch input and attach it to a multimeter probe. Disconnect the other multimeter probe from the other lead and touch it to the engine block ground. Measure the voltage. The voltage
must be 1.5 VDC or less.

If the voltage is
not correct, there is an external voltage source connected to the circuit, or there is a short circuit between the cruise control/PTO ON/OFF switch circuit and a wire carrying power in the OEM harness. Remove the voltage source or repair the wiring in the OEM harness according to the vehicle manufacturer’s procedures. Connect all components after completing the repair.

NOTE: If the cruise control/PTO ON/OFF switch circuit was approved in all of the previous tests, it is functioning correctly.

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Last Modified:  30-May-2008

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