Cummins ISX11.9 CM2250 – Service Manual 019-254   Power Train Protection 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 powertrain protection 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 from the electronic control module (ECM). Insert the multimeter probe into powertrain protection switch signal pin in the OEM harness. Touch the other probe to the engine block ground.

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Move the powertrain protection switch to the ON position. The multimeter
must show a closed circuit (10 ohms or less). If the circuit is
not closed, inspect the signal wire for an open circuit. Refer to the OEM troubleshooting and repair manual. If the resistance is within specification, the signal pin
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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Isolate the powertrain protection switch circuit.

Touch multimeter probe to the engine block. With the other electrical lead inserted into powertrain protection switch signal pin, measure the resistance.

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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 powertrain protection switch circuit, provided that the switch has been previously checked. Repair or replace the wire connected to powertrain protection switch signal pin according to the vehicle manufacturer’s instructions.

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Check for Short Circuit from Pin to Pin

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Isolate the powertrain protection switch circuit. Place one of the leads into power train protection switch signal pin. Insert the pin of the other lead into pin 1. Connect the alligator clips to the multimeter probes. Measure the resistance.

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

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Remove the lead from pin 1, 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 powertrain protection switch signal pin and any pin that measured less than 100k ohms.

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

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Check for Short Circuit to External Voltage Source

TOC

Isolate the powertrain protection switch circuit. Turn the vehicle keyswitch to the ON position. Set the multimeter to measure VDC.

Insert the test lead connected to the positive (+) multimeter probe into powertrain protection switch signal pin of the OEM harness.

Disconnect the negative (-) multimeter probe from the test lead, touch it to the engine block ground, and measure the voltage. The voltage
must be 1.5 VDC or less.

NOTE: An external voltage source is any wire in the OEM harness wiring that carries the voltage.

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If the voltage value is more than 1.5 VDC, there is a short circuit between the wire connected to powertrain protection switch signal pin and a wire carrying power in the OEM harness. Repair the OEM harness according to the vehicle manufacturer’s procedures.

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Last Modified:  30-May-2008