TAZ 4 Dual Extruder

I installed the Marlin Dual Extruder Software and a dual extruder on my TAZ 4. My first extruder motor (E0) is fine, but my second extruder motor (E1) has constant current running to it even when it is not extruding. This is causing the motor to always run very hot.

We are thinking this is a defective Rambo board, but I’m open to suggestion (could it be firmware related?). Has anyone else had this problem?

what exactly do you mean by constant current? If you leave it idle and select Motors Off, does it still seem to have this issue? In operation, the stepper motors will normally have current flowing to them to hold the current position, even if they are not in motion. That would be normal. Is something happening that seems to be abnormal?

When I boot up the TAZ 4 (without filament in the extruders) I cannot spin extruder motor E1 by hand because the current it starts getting at boot up locks up the motor; however extruder motor E0 is fine at boot up such that I can spin that motor freely. After about 5 minutes, due to the constant current being sent to motor E1, it starts getting extremely hot.

Also, just to try something, do you know what gcode command to send in Pronterface to turn off extruder motor E1 (the second extruder)? Fyi, when I tried to extrude using software commands with motor E1 it would not turn, possibly due to the current running through it which might all be related to a defective Rambo board which would be a shame because my TAZ 4 is brand new.

…and by the way, when I click Motors Off in Pronterface, the extruder motor E1 still stays locked up…no way to stop the current going to it.

There is a good list of gcode here:


You can switch toolheads by entering “T0” and “T1”. M18 turns off the motors. I don’t have a dual here to confirm this will work for you.


Turns out it was a damaged stepper driver on the RAMBO board. Lulzbot replaced it free of charge because it was under warranty and took care of it pronto…thank you Lulzbot.

Dual extruder firmware is loaded, Esteps calibrated for both extruder motors, 2nd extruder offsets dialed into Slic3r. Currently trying to level the dual extruder heads in all four corner.