cj22

I’ve got a 2014 Mercedes GL 550 . i’m having several issues that have me completely stumped . I bought it used & the horn has never worked! I checked the fuse it appears to be fine. Right after i got it the seat massagers quit working . Now there is a malfunction code (picture below) showing up for the rising function. From what I’ve read this can be caused by a small leak in the airmatic system . I had it checked by a non mercedes shop they said it shows no leak. Now the command screen/radio/DVD players , nothing works. it started out with the screen just going blank then coming back on & resetting. Now it doesn’t come on at all. Except the on button flashes.
Things i’ve tried: Changing both the battery & auxiliary battery. Checked fuses for all horn, airmatic system, & command fuses , including the one on the back of the radio. i’ve tried resetting the radio , from a video i saw on youtube.

Has anyone had any of these issues? it seems crazy expensive at the dealership. Having to pay $279 for diagnostics & then crazy amount

picture of head unit label inside

on button flashes on & off

for replacement radio & it’s still might be outdated . Has anyone upgraded the radio/screen & made it compatible with the backup camera , current back seat screens, i’m not sure if i would still be able to access seat massagers ect. and it’s confusing which one would work since the radio controls , DVD changer & screen are separate. Picture/videos below. Any help would be greatly appreciated!

cj22

would it be compatible with current backup camera , back seat screens,
how would i use my seat massagers