check your brake lights often to make sure they are clean and working properly
towbar maybe or be sure that your tail lights and brake lights are in good working order.
Both.
Lower-back of engine (towards rear of vehicle). Accessible only by lifting the vehicle.
Depending on vehicle - usually at the lower rear end of the engine - follow the + battery cable
It is a valve in the brake lines going to the rear of the vehicle. It adjust the amount of fluid flow to the rear brakes depending on the height of the rear suspension. The lower the suspension, the more weight in the vehicle, the more rear braking power is needed.
sagging right rear spring
vehicle body networking is just a way to use less wire through-out the vehicle e.g instead of running a wire from the rear light to earth on the battery you just earth the rear light to the vehicles chassis.
Rear, lower, passenger side of engine. it is best reached from under the vehicle.
It is not safe to work under the vehicle iff it is running.
It's a height sensing valve. If the vehicle is heavily loaded the rear end sits lower and the valve allows more fluid to get to the rear brakes. When lightly loaded the vehicle sits higher and the opposite happens.
Front and rear part of vehicle that sticks out the furthest-lower part that hits any foreign object first