Electronic Control System Signature, ISX and QSX15 Engines – 019-024   Cruise Control or PTO Set/Resume Select Switch Circuit

General Information

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In addition to cruise control functions, the cruise control select switch also provides for increasing/decreasing idle speed, PTO speed, fault code flashout, and road speed governor limit.

 
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Resistance Check

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 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 cruise control/PTO set/resume select 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 a test lead into the cruise control/PTO set/coast switch signal of the OEM harness connector and connect the alligator clip to the multimeter probe.

Touch the other probe to engine block ground.

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Hold the cruise control select switch in the SET/COAST position. The multimeter
must show a closed circuit (10 ohms or less) while holding the switch in the SET/COAST position and return to an open circuit (100k ohms or more) when the switch is released. The circuit
must remain an open circuit (100k ohms or more) when the switch is in the RESUME/ACCEL position.

If the resistance values are
not correct, make sure the cruise control/PTO set/coast input and the cruise control/PTO resume/accel input wires are properly installed on the cruise control select switch. If both control wires are correctly installed, inspect the cruise control/PTO set/coast input and the cruise control/PTO resume/accel wires for an open circuit, provided the cruise control select switch has been previously checked.

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Remove the lead from the cruise control/PTO set/coast switch signal and insert it into the cruise control/PTO resume/accel switch signal.

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Hold the cruise control select switch in the RESUME/ACCEL position. The multimeter
must show a closed circuit (10 ohms or less) when the switch is in the RESUME/ACCEL position and an open circuit (100k ohms or more) when the switch is released.

The circuit
must remain an open circuit (100k ohms or more) when the switch is held in the SET/COAST position.

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If the resistance values are
not correct, make sure the cruise control/PTO resume/accel wire is properly installed on the cruise control select switch. If the cruise control/PTO resume/accel wire is properly installed on the cruise control select switch, inspect the cruise control/PTO resume/accel signal for an open circuit, provided the cruise control select switch has been previously checked.

If the resistance values are correct in the previous checks, the cruise control/PTO set/coast signal and cruise control/PTO resume/accel signal
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 from Pin to Pin

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Isolate the cruise control/PTO set/resume select switch circuit as described in the previous section. Insert a test lead into the cruise control/PTO set/coast switch signal pin of the OEM harness connector. Insert the other lead into the first pin in the connector. Connect the alligator clips to the multimeter probes. Measure the resistance.

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

Remove the lead from the first pin in the connector and check all other pins. The multimeter
must show an open circuit (100k ohms or more).

If the circuit is
not open, there is a short circuit from the wire connected to the cruise control/PTO set/coast switch signal pin and any pin that measured less than 100k ohms.

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

Remove the lead from the cruise control/PTO set/coast signal pin and insert it into the cruise control/PTO resume/accel switch signal pin. Insert the other lead into the first pin in the connector.

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

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Remove the lead from the first pin in the connector and measure the resistance to all other pins. The multimeter
must show an open circuit (100k ohms or more). If the circuit is
not open, there is a short circuit between the wire connected to the cruise control/PTO resume/accel switch signal pin and any pin that measured less than 100k ohms.

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

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Check for Short Circuit to External Voltage Source

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Isolate the cruise control/PTO resume/accel switch circuit as described in the previous section. Turn the vehicle keyswitch to the ON position. Adjust the multimeter to measure VDC. Insert a test lead into the cruise control/PTO resume/accel switch signal of the OEM harness connector. Connect the test lead alligator clip to the positive (+) multimeter probe. Touch the negative (-) multimeter probe to the engine block ground and measure the voltage. The multimeter
must show less than 1.5 VDC.

If the voltage value is
not correct, there is an external voltage source short circuit to the cruise control/PTO set/coast switch signal in the OEM harness. Remove the voltage source. Repair or replace the wire in the OEM harness. Refer to Procedure
019-071.

Remove the lead from the cruise control/PTO set/coast switch input pin and insert it into the cruise control/PTO resume/accel switch input pin. Touch the negative multimeter probe to the engine block ground and measure the voltage. The multimeter
must show less than 1.5 VDC.

If the voltage value is
not correct, there is an external voltage source short circuit to the cruise control/PTO resume/accel switch input pin in the OEM harness. Remove the voltage source. Repair or replace the wire in the OEM harness. Refer to Procedure
019-071.

Connect all components after completing the repair.

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Last Modified:  30-May-2008