Limit Switch Troubleshooting for "M" Machines

Owned by Sam Bollen, created
Last updated: Mar 07, 2023

Background

Limit switches are the referees of your machine travel. They set your boundaries and stop you from going out of bounds. Listed below are some helpful troubleshooting tips, in the event you are having limit switch issues.

Table of Contents

Limit light is always on, even though the switch is not actuated

Input Status Reported from the Status Tab

Test to Perform on the Wiring at the ECM Board

Input Status Reported from the Status Tab

Test to Perform on the Wiring at the ECM Board

The X Limit light is always on, even though the switch is not actuated.

Jumper wire 409 to 414 on the ECM Board.

The Y Limit light is always on, even though the switch is not actuated.

Jumper wire 410 to 414 on the ECM Board.

The Z Limit light is always on, even though the switch is not actuated.

Jumper wire 411 to 414 on the ECM Board.

Results and conclusions:

  • If the light doesn’t go out when the terminals are jumped, the ECM board is defective.

  • If the light goes out when the terminals are jumped, the wiring has a break or the limit switch is defective.

  • If the diagnostic light is off, the wiring is OK and the switch is defective.

  • If the diagnostic light is on, the wiring has a break or defective connection.

Limit light is never on, even though the switch is actuated

Input Status Reported from the Status Tab

Test to Perform on the Wiring at the ECM Board

Input Status Reported from the Status Tab

Test to Perform on the Wiring at the ECM Board

The X Limit light is never on, even though the switch is actuated.

Remove wire 409 on the ECM Board.

The Y Limit light is never on, even though the switch is actuated.

Remove wire 410 on the ECM Board.

The Z Limit light is never on, even though the switch is actuated.

Remove wire 411 on the ECM Board.

Results and conclusions:

  • If the light doesn’t go on when the wire is removed, the ECM Board is defective.

  • If the light goes on when wire is removed, the wiring has a short or the limit switch is defective:

    1. Power off the machine. Then, disconnect wires from the switch and tape the end of each wire to prevent shorts.

    2. Power on the machine.

    3. If the diagnostic light is on, the wiring is OK and the switch is defective.

    4. If the diagnostic light is off, the wiring has a short circuit.

 

If you continue to have issues, contact Tormach Technical Support.