The engine torque limit switch allows the operator to switch to a different torque output limit by the engine. This is desirable in applications where auxiliary equipment can not handle full engine torque.
Activating this switch protects the equipment by limiting the maximum output torque of the engine. This maximum torque value can be entered through the electronic service tool under the powertrain protection feature.
Locate the engine torque limit 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.
NOTE: The torque limit switch is programmable by the OEM. The open or closed position of the switch can represent “Normal” or “Torque Limit” depending on how the OEM programs the switch. Before continuing troubleshooting refer to the OEM literature to determine how the switch is programmed and apply the “switch failed” criteria accordingly when performing the troubleshooting.
Place the switch in the torque limit 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.
Place the switch in the normal 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.
Touch one of the multimeter probes to one of the switch terminals. Touch the other probe to chassis ground. Move the switch to the normal 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.