Abstract: A brake light illumination system for use with engine braking includes an automatic illuminator switch connected to an engine retarder output line. The automatic illuminator switch is configured to be in a closed position relative to the engine retarder output line when an engine retarder is actuated and in an open position relative to the engine retarder output line when the engine retarder is in an inactive state. The brake light illumination system also includes a diode connected to the automatic illuminator switch. Upon actuation of the engine retarder, the automatic illuminator switch and the diode are electrically connected to a brake light switch to illuminate a plurality of brake lights.