Left stepper not working - can you help me diagnose further?

Hi! FlashForge Creator Pro owner here, board VSF7.7.

Right extruder prints great; left extruder not at all. See below for all the tests I have done to try to diagnose the cause. At this point I feel all the mechanicals are working and it's coming down to logic boards, but I don't know what / how to test next.


1. In Load/Unload Filament - motor does not advance
2. In printing from left extruder, filament does not come out.


TESTED:
A. Nozzle is clear. I can push filament through when it is hot OK
B. Teeth are in great shape, unclogged and perfectly aligned with the "V" on the guide wheel.
C. Stepper motor is functional. I can perform the LED test on both pairs of leads and LED lights up when motor is turned
D. Stepper cable is OK. I tested continuity on all 4 wires and they are fine
E. Connectors are fine. They are all well-seated.
F. Test voltage to Stepper Driver board. 5.0V when machine is powered ON


FAILED:
* Set left extruder to "Unload Filament". Test voltage across both pairs - 0V


What should I do next?


Thank you for your ideas!

I had the same thing happen to me. It was my fault as I tried to work on the hotend while powered on. I smoked the stepper motor driver. It's on the main board. If you follow the wiring from the motor to the main board you can see which one it is. If you want to be sure you can swap the one form the working side. I used the printer while I ordered a new one by taking out the bad driver.
If you look on the USA FF site they sell them for 16 bucks ( I bought 2 as I'm prone to blowing things up). No soldering, it's just a plug in module.

Hello dot.tom. Now, what I will suggest is to check the thermocouple of the left extruder of the heater. If you are able to find the heater embedded in the left extruder and on top of the left extruder nozzle, you will find the thermocouple embedded in the left extruder and on top of the left extruder nozzle as well, which is located right beside the heater. The thermocouple, without wires, has the shape of a hexagonal screw. You can then check if the thermocouple is working properly. If the control unit does not read the temperature through the thermocouple, the heater/hotend will not heat up. If you are not able to find the thermocouple at the left extruder, or if you don't know how to check if the thermocouple is working properly, let me know and I will tell you what to do then.
Good luck!
3d_Printer_Worker
Hint: Contact me with the number 403 9781007 or with "wuyukun89@163.com" for more info!