3 on right (space) then light? That's code 23, low battery voltage.
Here are the light values from right to left
128, 64, 32, 16, 8, 4, 2, 1
So you would add 1, 2, 4, and 16 for the code
How can you tell what error code has come up on the display? I have 3 solid lights on the right hand side and then a gap then just 1 solid light on its own
The error code will flash on the battery indicator by the operator handle (key switch) it will be a series of light and blank bars on the indicator.
You'll need a handset to plug into the controller. Let me know if you have one and I can tell you how to get the codes.