Getting Power to SMI DUO Braking System on 2017 Ford Focus

Updated 06/06/2017 | Published 06/02/2017

Question:

Installing SMI DUO proportional braking system on 2017 Ford Focus. Looking at your video, it appears you are connecting the system to the positive terminal on the battery and also attach to the negative battery chassis ground lug. Because the Focus must be disconnected from the negative battery terminal, how does the braking system get + and - 12 volt power? We have cutoff switches on both the negative battery post and the positive battery post to make sure no juice makes its way to the vehicle wiring which would possibly destroy the transmission. That's the first question. The second question is, why is the SMI braking system being activated when the turn signals are used? Which wire is connected wrong? The SMI braking system works fine when I push the motorhome's brake, but it also is being activated when I use a turn signal. With each turn signal blink, the towed vehicle's brake pedal is punished by the SMI braking system. We must have some wire wrongly attached somewhere. Any help?

asked by: David L

Expert Reply:

I spoke with a representative of SMI, and they informed me that when using their Stay-IN-Play DUO, # SM99251, you should disconnect the positive cable from the battery, not the negative cable, despite what the owner's manual says. Then you should run the power wire between the positive post and battery disconnect.

I also asked SMI about the braking system being activated when the turn signals are used. They said it was likely that this was happening because the sensitivity knob is set too high. Take a look at the instruction manual, which I have included a link to, and look at "Step 12: Adjusting the G-Force Controller," and that should eliminate the problem for you.

expert reply by: Kyle S