beemerphile1 wrote:
I don't know anything about your vehicle but will make a WAG that may be the answer.
Some vehicles that have 'drive by wire' incorporate a brake disable of the throttle. If you have 'drive by wire' that may be what is happening. When you activate the brake it shuts down the throttle.
That should be the correct answer.
The deal is with modern day vehicles they use what is called "drive by wire". Simply put what that means is instead of using a direct steel cable from the gas pedal to the throttle plate (which is what was used years ago) your gas pedal is now connected to the engine computer.
The engine computer takes the gas pedal position info and operates the throttle plate via a small servo motor.
However due to several famous runaway vehicles and a huge recall, the NTSB now requires ALL vehicles using "drive by wire" to have some sort of brake override system.
What this means to you is you can no longer ride (or touch) the brakes while driving above idle speed.
If the computer detects the BRAKE signal at the same time as you are pressing the gas pedal the computer COMMANDS the throttle plate to close.
What does that have to do with your problem?
Many brake controllers are actually wired to LIGHT the brake lights if the manual override on the controller is activated.
Basically your controller as wire is giving the engine computer a false brake signal.
Can this be fixed?
Not sure if it is possible to do since your controller depends on getting the brake light signal to activate the controller under normal usage. If you disconnected the brake light wire then the controller will not work since it wouldn't get the signal from the car.
The only things I can think of is find a different controller which either does not send a brake light signal while using the manual override or can be configured to not send that signal to the car.
Alternately if you are handy with electronics it is possible to wire a diode to the brake light wire. The diode can act as a one way device letting the car to controller signal through but blocking the controller from sending a signal to the car on the same wire.
