Y axis moving but not homing

Trying to figure out what’s happening on my y-axis as it’s behaving badly. I’ve had some electrical issues so rewired my x and y axes a few weeks ago. Everything’s been working fine until recently when my y- axis stopped homing unless it was less than 100mm from the home position.

I’m running a primo on a MKS gen L board with dual endstops. I can fast-move and jog the y axis in any direction (faster than a homing love) over the entire length of the cutting area (including a 500mm fast move), but when I try home the one motor will not engage. Switching the motor connections on the board changes which motor is impacted implying it’s a board issue. I’ve tried disconnecting the endstops and that’s not working. I’ve also swapped stepper drivers and tested, but no joy. Considering replacing the motherboard but hoping for an easier/faster solution. I’m a bit stumped so any suggestions welcome.

A few things:

  1. The endstops are triggered when you disconnect them. So homing with no endstops should not work.
  2. The “BED_SIZE” is set in the firmware. I believe 509- had it set to 300mm and 510+ has it set to 600mm. If you are farther than that size, then homing will fail. It has no other purpose, so just make sure you home from nearish the endstops.
  3. M119 is the best way to debug your endstops. If you send this from repetier host, it will report back what it thinks each endstop is doing. All of the logic after that is very well tested. If it reports correctly in M119, you’re 99% of the way to homing properly
  4. The endstops do not restrict motion when not homing.

Given all of that. My guess is that one endstop on your Y is not connecting. You can check with M119. You can also try swapping Ymin and Ymax to confirm. If you do, the other motor will start homing, but you’ll still have a broken wire somewhere.

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Thanks Jeff. It’s definitely within the cutting area set in marlin so it could be the endstop wiring. I’ll give that a test and let you know.

Genius. It was the endstop wiring. Fixed and working now - thanks Jeff!

Had a few problems with the cable I originally used to wire up - it was pliable twisted copper, but despite being in a cable chain it’s still breaking from moving around. Upgrading all my wiring to prevent a further issue.

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