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Mounted MA EZ-Pass behind front grill: here's how

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I mounted my MA EZ-Pass behind the front grill of my Model S, so I thought I would share my technique for other's benefit. As a side note, I hate the way that EZ-Passes look when mounted on the inside of the windshield, and I've heard that the coating on the windshield gets in the way of it functioning.

Two quick photos of exactly what the MA EZ-Pass looks like. So you can get a sense of the dimensions.
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First I removed the section of the front grill/cone based on the technique detailed in prior posts here (using a credit card to pop the hooks that hold it in... quite easy)
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More detail of it coming off
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Here you can see that the transponder is too large to fit into the hole without sliding it behind the cone first. My first idea was to mount it on the back of the piece I removed, and simply replace the piece. But it was clear at this point that the transponder was going to be too large. So, my idea was to mount it to the piece I removed, but bump it out enough to clear the tabs that hold the piece I removed in the cone.
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To bump it out, I used a piece of foam weather seal that I had from an old weather sealing project. The key here is that it goes out far enough to clear the hooks that clip the piece into the cone. This way I could slide the transponder/piece combination into the hole, but it wouldn't pop off once resealed.
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I used command strip velcro to hold the transponder + foam to the cone piece. I did this so if I needed to move it up/down/sideways it would be easy (plus it gave me a few more mm of clearance).
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Here you see the combined unit. Note how the transponder is mounted "up" higher than the top of the cone piece and out ahead of the clips. This way it will fit up and into the space behind the cone.
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And, finally, here is a very hard to capture shot of the unit being replaced. I had to slide it "up and into" place, to keep the transponder attached.
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Hope that's helpful for anyone else who attempts this project.
 
That is excellent, thanks for documenting the procedure. Two questions: is that the Signature style nose cone with the lip (it looks like it), or is that the Production smooth cone? And second, can the transponder be successfully read from nside the nose cone?
 
Bad news... I went through the toll booth today, and it didn't seem to register. I understand that there is a front license plate mounted option, and I'm thinking that perhaps that might work better (mounted behind the nose cone). Side note: I'm driving without a front plate... I also hate those :)... so mounting to the front plate is not an option either. I'm going to deal with it again this weekend.
 
Bad news... I went through the toll booth today, and it didn't seem to register. I understand that there is a front license plate mounted option, and I'm thinking that perhaps that might work better (mounted behind the nose cone). Side note: I'm driving without a front plate... I also hate those :)... so mounting to the front plate is not an option either. I'm going to deal with it again this weekend.

Thanks for working on this issue. I think the front license plate mounted transponders are quite a bit longer, but much narrower, so it might be a better fit anyway.
 
Bad news... I went through the toll booth today, and it didn't seem to register. I understand that there is a front license plate mounted option, and I'm thinking that perhaps that might work better (mounted behind the nose cone). Side note: I'm driving without a front plate... I also hate those :)... so mounting to the front plate is not an option either. I'm going to deal with it again this weekend.

I'm surprised that it didn't work. It may have something to do with the horizontal orientation or that it doesn't protrude enough beyond the metal frunk lid. The plastic should not block the signal.
 
I'm surprised that it didn't work. It may have something to do with the horizontal orientation or that it doesn't protrude enough beyond the metal frunk lid. The plastic should not block the signal.

I suggest going with my solution because the bonnet may act like a large antenna array. If that does not work then go with Bonnie's idea.p of holding the EZ pass out the window.
 
I moved the transponder down 1/4 inch, and went though the toll booth.... And it WORKED! Super exited.

There is a chrome strip above the punch out, and I think when it was mounted higher it was blocked by that strip.

Figured it was something like that. This was the best Model S news of the day!:) Thanks for your persistence on behalf of all of us. Now we just need someone to try this with the new production nose cone, although I can't think of any reason why it wouldn't work with it as well.
 
Yes that is great news, and now Pennsylvania needs to adopt the smaller transponder! Though perhaps with the new one-piece nosecone, you could just slap the velcro on the inside of the code and be done with it, no matter the size of the transponder.