Brake Controller Problems

To Quick
should read auto downshifts a gear

Phill H

check LCOOL

Many modern autos drop a gear when you brake. ie from 4th to 3rd. Corolla's do this, so the same feature will be in other vehicles and other makes too. Unfortunately you didn't say what vehicle it is in.

It detects the fact that you have applied the brakes and most likely some reduction in speed too so it is trying to match the vehicle gear to the new road speed. Especially good if you have to accelerate as it is already in the appropriate gear.

Some modern vehicles have four wires on the stop light switch.
2 for the ecu and power in and out for the brakes.
It is possible yours isn't wired exactly as it should be so the lever action doesn't activate the gear change. But it will activate when the pedal is pressed.
However, if it is only a two wire stop switch, it may have to work that way as when you use the lever you are wanting it to reduce speed anyway.
If it is a problem it can be wired with a diode blocking the return current to the switch terminal.
I don't see this as a problem though because you want to stop/slow down and if really using the lever, the box will drop a gear but the trailer will be braking harder than the degree of speed drop of the box = no problem.

Thanks everyone for all the reply's I now know how and why it works

Thanks again

Phill H