Cummins ISX11.9 CM2250 – Service Manual 019-265   Accelerator Interlock Switch Circuit

The accelerator interlock switch is programmable. Check the setting with INSITE™ electronic service tool before continuing with the troubleshooting steps.

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

NOTE: The accelerator interlock signal input can also be used as the engine torque limit switch signal as well.

Disconnect the original equipment manufacturer (OEM) harness connector from the electronic control module (ECM). Insert a test lead into the accelerator interlock switch signal pin. Touch the other multimeter probe to engine block ground. With the switch in the inhibit position, the multimeter
must read an open circuit (100k ohms or more).

With the switch in the normal position, the multimeter
must read a closed circuit (10 ohms or less).

If the circuit is
not closed, inspect the accelerator interlock switch signal line for an open circuit.

Connect one of the multimeter probes to the accelerator interlock switch signal wire. Touch the other probe to chassis ground. Move the switch to the inhibit position and measure the resistance.

The multimeter
must show an open circuit (100k ohms or more). If the circuit does
not show an open circuit then there is a short to ground in the circuit somewhere.

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

Check for a short circuit from pin-to-pin. Insert a test lead into the accelerator interlock switch signal pin. Insert the other test lead into the switch return pin. Measure the resistance. The multimeter
must show an open circuit (100k ohms or more).

Remove the test lead from the switch return pin and test all other pins in the connector. The multimeter
must show an open circuit on all pins.

Repair any pin circuits that show a closed circuit with the accelerator governor switch signal pin.

Set the switch to normal position and set the multimeter to read VDC. Insert one test lead into the accelerator interlock switch signal pin and connect a multimeter lead to it. Touch the other multimeter lead to engine block ground. Measure the voltage.

The voltage
must read 1.5 VDC or less.

If the voltage is
not correct, there is an external voltage source connected to the circuit. Repair or replace the OEM wiring. Refer to Procedure
019-071.