I found the Cadillac XT4 Owner Manual (see specific post), but on page 270 under "VEHICLE CARE" it mentions:
For the proper type of replacement bulbs, or any bulb changing procedure no listed in this section, contact your dealer.
Do not replace incandescent bulbs with aftermarket LED replacement bulbs. This can cause damage to the vehicle electrical system."
I find this worrying because I did replace ALL (100%) of the incandescent bulbs (interior and exterior) in my two previous GM vehicles (1995 Buick Regal LS, 2009 Chevy Equinox 2LT), and no damages have been "caused". On the next page (271), the illustration of the bulb for the "Back-up Lamps" looks like it is incandescent.
So if you need to know if the two backup lamps are "white" the dealer must power on the vehicle and shift into reverse to illuminate the lamps. Cadillac is warning owners not to replace those bulbs for LEDs.
Last edited by Raymondjram; 10-16-2018 at 09:57 AM.