First off I want to say that I'm a beginner in electronics so I may be wrong in any of my statements.

So, I got this Milwaukee M18 CBLID impact driver and I was thinking on updating to the new fuel series because it have a speed control such as this model does, but my tool works fine and I'm just missing the speed control so I thought maybe I could replicate the system so I proceeded to disassemble the tool to see how it works. The following is the inside of the tool.

enter image description here

From the inside the connector have 4 ports, left one being voltage, 2 in the middle called J1 and J2 which look like data transfers and finally the ground at the rightest. Here is a better picture of the connector:

enter image description here

UPDATE 1: Placing a buck controller is no longer possible due to the BLDC being PCB controlled.

Seems like the PCB of this model which has speed control is the same as mine, but in mine the speed control terminals are unused as the following picture shows, so the goal now is to replicate the speed control on the tool I just told you about which seems to work with a hall controller, or find a way around using any other component.

enter image description here

If you need additional pictures to understand anything of the tool just say it and I will update the post with them.


  • 1
    $\begingroup$ I suspect your issue won't be with analog circuits, it will be with the IC's on the PCB. The speed is almost certainly controlled digitally, plus your trigger isn't set up for speed control. $\endgroup$
    – Tiger Guy
    Aug 20 at 16:18
  • $\begingroup$ Yes, it is all in the trigger assembly. Not something you can readily hack. $\endgroup$
    – Phil Sweet
    Aug 20 at 22:42
  • $\begingroup$ the hall sensor is used to make the speed select circuit impervious to dirt ... the output of the hall sensor is probably open collector ... try using a 4.7 Kohm resistor to jumper SS to GND $\endgroup$
    – jsotola
    Aug 21 at 19:18
  • $\begingroup$ That looks like a 3-phase BLDC (6 FET-s). It may have a controller IC. Check the part number online. If that is not a microprocessor, you may have some more hope. $\endgroup$
    – jay
    Aug 31 at 18:36

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