Abstract: A brake monitoring system is disclosed. The monitoring system includes a primary braking system located in a towing vehicle. A towed vehicle is releasably attached to the towing vehicle. A towed vehicle braking system is mounted in the towed vehicle. An auxiliary braking device is configured to activate the towed vehicle braking system and to sense at least one parameter of the auxiliary braking device or of the towed vehicle braking system. A transmitter is in communication with the auxiliary braking device. The transmitter is configured to send a signal about the parameter. A receiver is located in the towing vehicle. The receiver is configured to receive the signal from the transmitter. A display is located in the towing vehicle and is in communication with the receiver. The display is configured to display a message to a towing vehicle occupant about the parameter.