Solved Printer Goes Wild

Well I have been reading about all these problems here and being thankful that it hasn't happened to me and out of the blue epic fail.

I used the printer last night and printed a 6 hour print with no problem. Today I loaded an stl from Fusion 360, ran through the repair in Meshmixer, imported into Matter Control and exported the g code on to an sd and started to print. I believe it went through the bed leveling OK I think and then it started the print and almost immediately the head slammed into Z support on the X+ side. I shut it down and recycled the machine.

Then it started doing a strange pattern leveling and wanted to print about 3/8" above the bed. Thinking it must be the print file or maybe the xxl controller I hooked up the computer and tried to print a simple calibration cube. The printer went through the leveling in the normal pattern however at about half of the points it reversed well above the bed and went on to the next position and when it printed it was well above the bed.

Any idea what would cause it to go wild after it just printed fine the night before.

Thanks in advance for your help

 

Definitely not disconnected or loose, but I will check with a meter for proper operation, thanks

 

Checked bed is pretty level just moving the x across the bed at different y positions and the switches are in the proper position. Early morning tomorrow so I will take it apart tomorrow and check the switches with a meters. Funny part it is consistently the same bed level positions that don't hit the bed. Position 3, 4 and 9

 

I can see the logic with the switch breaking contact prematurely and causing the bed leveling issue, but what would account for the head slamming into the Z support on the X+ side?

 

Well I don't know what to say. I came home last night and tore the printer down. All limit switches were properly secured and wires connected. Removed the limit switch wires and checked for proper operation with an ohm meter, all good. Checked all connections again including the board connections, again all well no signs of rubbing or strained wires.
Reassembled and ran a print to test. This time all points on the bed leveling points hit and when it started to print it was about 30 mm's above the bed. I screwed the Z rods down to the bed and leveled across the bed, ran a print and all is fine now.
So thanks for your help and input, if nothing more I learned a little more about the machine which is a good thing. Just wish I know exactly what caused and resolved the original problem.