Yes, you do need to add two diodes to make it work thru an AIU. I have the diagram in my files to make it work. It is a complicated diagram and was hard to figure out exactly where to put it. I will dig it out and get it put up for discussion. Probably tomorrow based on when I find it. As much as I can recall, two added diodes control reversing of DC can motor for up & down. As joe says, be patient, I blew the can motor when experimenting.
When I worked it out, it was a big deal and took a lot of analysis time. . I had to reverse engineer the boards in controller & on unit.
That is why the diagram is required to explain.
I can tell you to use it to my satisfaction, it takes 4 ACC ports.
1. Turn bucket on/off (no diode required)
2. take bucket up on/off
3. take bucket down on/off
4. Operate solenoid to fill waiting car. (no diode required)
