The SRS impact sensors are actually in the module under the
ashtray. The grille guard is a good idea because it can save your
frame which tend to crinkle with even the lightest hit.
Our body shop has us do the frame replacement for them on
wrecked ML's. Some have been pretty light hits.
I can tell you, swapping out a frame is a BIG HUGE NASTY P.I.T.A.
DR.D