Home » ISX11.9 CM2250 - Service Manual » Cummins ISX11.9 CM2250 – Service Manual 019-382   Maximum Engine Speed Switch

Cummins ISX11.9 CM2250 – Service Manual 019-382   Maximum Engine Speed Switch

General Information

TOC

The maximum engine speed switch is an OEM installed switch that allows a driver to select a lower, programmable maximum engine speed. Certain applications such as one that uses a hydraulic system may need to be protected from an overspeed condition. The operator may toggle this switch and limit the maximum engine RPM to a lower value that is safe for the hydraulic system to operate in.

NOTE: The switch is now programmable, meaning the speed limit and normal positions can either be open or closed depending on the configuration. Confirm which configuration the specific switch is and adjust the troubleshooting failure criteria before deeming the switch failed.

 
SMALL | MEDIUM | LARGE

Resistance Check

TOC

If INSITE™ is available, monitor the maximum engine speed switch for proper operation. If not, follow the troubleshooting procedures in this section.

Locate the maximum engine speed switch. Label the wires with the location of the switch or the wire number. Remove the electrical connectors from the switch. Adjust the multimeter to measure resistance. Touch one multimeter probe to one of the terminals on the switch. Touch the other multimeter probe to the other terminal of the switch.

Place the switch in the open position and measure the resistance. The multimeter must show an open circuit (100k ohms or more). If the circuit is not open, the switch has failed. Refer to the OEM troubleshooting and repair manual for replacement procedures.

SMALL | MEDIUM | LARGE
   


Place the switch in the closed position and measure the resistance. The multimeter must show a closed circuit (10 ohms or less). If the circuit is not closed, the switch has failed. Refer to the OEM troubleshooting and repair manual for replacement procedures. If the resistance value is correct, the switch must still be checked for a short circuit to ground.

SMALL | MEDIUM | LARGE
   

Check for Short Circuit to Ground

TOC

Touch one of the multimeter probes to one of the switch terminals. Touch the other probe to chassis ground. Move the switch to the closed position and measure the resistance. The multimeter must show an open circuit (100k ohms or more). If the circuit is not open, the switch has failed. Refer to the OEM troubleshooting and repair manual for replacement procedures. If the switch passes all of the previous checks, the circuit must be checked for an open circuit, a short circuit to ground, a short circuit from pin to pin, and a short circuit to an external voltage source.

SMALL | MEDIUM | LARGE
Last Modified:  12-Mar-2002