Finally figured it out today, so ignore my previous posts!
But I do have a new question... how in the heck do you re-seat the rubber grommet back into the firewall?
I feel your pain. I struggled for a long time trying to get the power wire and the front camera cable through the firewall. (Although firewall may be a misnomer, because there is no IC engine.) Almost all the videos on this subject are WRONG, because they apply to older M3's. All the holes that use to be there are non-existent anymore. I tried piercing the grommet through which you used, but I had difficulty seeing both sides. It seemed like the passenger side of the grommet was hidden behind the main computer enclosure, even when I removed the glovebox and airbag. I went through the grommet on the driver's side, since there are less OEM wires passing through it. And don't go around the outside of the grommet as was suggested in another video. That's a BAD IDEA. See the video link below for driver's side grommet puncture:
Unfortunately, my alternate route required splicing and running the power wire and video cable separately from the main cable. I actually was able to pierce the little "nubbins" along the periphery of the grommet, which are still insulated and protected from the metal punched out hole in the firewall. Again, unfortunately, I had to cut the video cable to get it through the new hole in the grommet, since the connector is so large, and then I reattached the video cable wires and shield. The latter is not so easy, unless you are use to reattaching video cables containing 3 wires, an aluminum shield and a ground wire. And I might point out that there is no easy way to connect to the positive terminal on the newer Tesla Model 3 vehicles. What's with that goofy flat positive plate with the grooves and the plastic cap? It wasn't easy to fit a metric M3 bolt, star washer, modified lug, and a locking nut inside that red plastic cap.
I would also advise to try to avoid removing the airbags, since this turned out to be a nightmare. There are held in place with e10 External TORX bolts and RED ThreadLock. This requires the use of e10 sockets which I assume most people don't have,. I eventually had to purchase an excellent socket from Amazon:
Hazet 850-E10 Socket 1/4" Square Torx E10)
The cheaper ones from local stores are worthless, because they don't grab the entire bolt. If you reuse the e10 bolts, then you have to clean the threads with acetone and an M6 die, and then clean out the anchor holes with an M6 tap. You really can't properly torque the bolts to 8 Newton-Meters unless you clean the threaded holes. Oh yeah, most of us don't have a torque wrench that goes that low. Another expense. You could just buy new bolts from Tesla (59 cents), but they are not as hard as the originals (metric property scale 8.8), and they have the BLUE ThradLock.
In answer to your last question it is very easy to dislodge those large grommets which I know all too well. You have to just grab the edges with your fingertips and go around the perimeter of the grommet about an inch at a time. If you lubricate the wires first with a a silicone grease that is compatible with wire insulation, it is less likely to dislodge the grommet.
I’m just starting to create content so go easy on me!
