I don't know what system you purchased and installed, but I had bought one cheap and not-so-good ultrasonic system for the BMW and had a 'bumper' four-sensor installed in the RX350. Both work off the back-up light (wire to the bulb) and do not trigger any bulb-check. At worse, if yopur system consumes so much energy that it triggers the bulb-check, you might want to have the back-up light trigger a relay instead, and the relay allows the passage of current to your system?
Thanks for the reply. To clarify: system worked great with backup light engaged. Relay is good idea, but the problem is the aftermarket system worked great with the engine OFF and access position of the ign key engaged. Only when the RX was running did it give gibberish which my WAGuess was related to some bulb-check interference. Was just trolling for a successfull BTDT as this system was installed 5 yrs ago.