mercdude
Well-known member
Hello All. I'm super new to TDI's, but not to wrenching on cars. I recently picked-up a 13 JSW TDI, manual trans (base model), and I've been spending the last few months throwing on a few extra goodies that I consider essentials. One of these, and pertinent to this discussion of MK5-6 Jettas, is an auto dimming rear view mirror with homelink.
I know there's a guide for this installation found here via my turbo diesel, but I wanted to clarify a few issues with the writeup and hopefully prevent anyone else from struggling to get this fairly easy install completed. I found the 'writeup' missing important information that made it difficult to follow and confusing.
First thing first. I'd suggest buying a used Gentex 453 mirror with a 3 wire pigtail off ebay. You can get other models, just make sure they have a clip-in for the wire cover (the mirror's mount has 2 slits that the wire cover fits inside). The 453's can be had from a donor vehicle (i.e. Kia) - doesn't matter. You also want to pickup (if not included) a Gentex specific, extendable wire cover/bracket. Also, I'd suggest forgetting about buying a VW to Gentex adapter bracket (aka mirror button) for $50. Instead, just swap it out with the correct mount (common wedge shape) and forgo the expense and sloppy install of the adapter.
Here's how you do that. Contrary to what every glass shop I talked to said about the mirror button removal, it can very easily be done without damaging your glass. Just take a pencil torch, throw heat on the button for about 30 seconds, at the same time take a razor blade and slice through the glue. In under a minute, your mount is off. Make sure you are prepared with rags to catch the now very hot VW button. Now clean the area with your razor blade and then promptly take your vehicle to a glass shop to get the correct mirror button professional installed for about $30. Don't even mess around with store bought rearview mirror adhesive - to get a mount to permanent affix to a windshield takes more than just glue: it takes primer, sanding, cleaning, etc. Just let a pro do it and save yourself the hassle because last thing you want is a now wired up mirror falling off in 4 days!
Okay, steps so far: 1) acquire auto dim/homelink mirror with 3 wire pigtail 2) get wire cover 3) remove vw's button and replace with new button.
You'll also need a few extra things like electrical t-taps (for splicing) and a crimp-on loop, sheet metal screw, bailing wiring, electrical tape, small drill bit, etc.
Now comes installation. Hardest part: get the wiring through the overhead light area and under the headliner out to the mirror. I used bailing wire from the overhead light area in combination with a plastic bone tool to gently (!) pry at the headliner to open a space large enough to get the wire through. This will take some practice. Hint: just to the left of center of the overhead light area is a small 1/2" wide area that you can thread the wire through. Once through, use a phishing tape process to pull the wiring up to the light area. Now install the mirror, attach the wiring pigtail, and then slide into place the wire cover. Depending on the length of your wire cover, it'll be a tight fit and requires some fan-angling.
Now the confusing part. The 3 wire gentex has a ground, constant 12v (for homelink) and switched 12v (for auto dim). In the my turbo diesel guide, the write up says that the left red with blue wire is switched power and the constant 12v is brown with blue. Wrong - at least with my non-moonroof vehicle, it's the reverse. The red with blue (far left) is constant 12v and the brown is switched (sorta - more on that in a second). So wire in your homelink wire on the red with blue wire using a t-tap connector. There won't be an oem place to conveniently install a grounding wire so just drill a small hole in the overheadlight bracket sheetmetal and put a sheetmetal screw. There you will install your crimp-on loop and ground wire.
Now choose your adventure. For the auto dim, ideally you want a true ignition switch on 12v source. The brown wire is switched, but only sort of. The brown wire is a timed constant 12v, so if you use it as your switched source for the auto dim, the mirror will turn off only in the following circumstances: 1) alarm//lock the car 2) 15-20 (?) minutes after leaving the car unlocked 3) manually turn on the overhead lighting 4) every time you open a door. It works without flaw, but it's a bit funky to see your mirror power switch on/off for 30 seconds every time you open the door.
In my universe, that's not the best. So I'd suggest doing a bit more work and tapping into the headlight switch wiring. To do this, take off the left A-pillar trim, using a guide wire/phishing technique, pull wire through the headliner, down the a pillar, down under the dash and use a t-tap on a true 12v switched source there (I think a purple/black wire, 2nd from top left).
Anyways, your final result will be professional and clean.
Reminder: wash your hands thoroughly before messing with headliner and be very gentle when prying. Hope this helps!
I know there's a guide for this installation found here via my turbo diesel, but I wanted to clarify a few issues with the writeup and hopefully prevent anyone else from struggling to get this fairly easy install completed. I found the 'writeup' missing important information that made it difficult to follow and confusing.
First thing first. I'd suggest buying a used Gentex 453 mirror with a 3 wire pigtail off ebay. You can get other models, just make sure they have a clip-in for the wire cover (the mirror's mount has 2 slits that the wire cover fits inside). The 453's can be had from a donor vehicle (i.e. Kia) - doesn't matter. You also want to pickup (if not included) a Gentex specific, extendable wire cover/bracket. Also, I'd suggest forgetting about buying a VW to Gentex adapter bracket (aka mirror button) for $50. Instead, just swap it out with the correct mount (common wedge shape) and forgo the expense and sloppy install of the adapter.
Here's how you do that. Contrary to what every glass shop I talked to said about the mirror button removal, it can very easily be done without damaging your glass. Just take a pencil torch, throw heat on the button for about 30 seconds, at the same time take a razor blade and slice through the glue. In under a minute, your mount is off. Make sure you are prepared with rags to catch the now very hot VW button. Now clean the area with your razor blade and then promptly take your vehicle to a glass shop to get the correct mirror button professional installed for about $30. Don't even mess around with store bought rearview mirror adhesive - to get a mount to permanent affix to a windshield takes more than just glue: it takes primer, sanding, cleaning, etc. Just let a pro do it and save yourself the hassle because last thing you want is a now wired up mirror falling off in 4 days!
Okay, steps so far: 1) acquire auto dim/homelink mirror with 3 wire pigtail 2) get wire cover 3) remove vw's button and replace with new button.
You'll also need a few extra things like electrical t-taps (for splicing) and a crimp-on loop, sheet metal screw, bailing wiring, electrical tape, small drill bit, etc.
Now comes installation. Hardest part: get the wiring through the overhead light area and under the headliner out to the mirror. I used bailing wire from the overhead light area in combination with a plastic bone tool to gently (!) pry at the headliner to open a space large enough to get the wire through. This will take some practice. Hint: just to the left of center of the overhead light area is a small 1/2" wide area that you can thread the wire through. Once through, use a phishing tape process to pull the wiring up to the light area. Now install the mirror, attach the wiring pigtail, and then slide into place the wire cover. Depending on the length of your wire cover, it'll be a tight fit and requires some fan-angling.
Now the confusing part. The 3 wire gentex has a ground, constant 12v (for homelink) and switched 12v (for auto dim). In the my turbo diesel guide, the write up says that the left red with blue wire is switched power and the constant 12v is brown with blue. Wrong - at least with my non-moonroof vehicle, it's the reverse. The red with blue (far left) is constant 12v and the brown is switched (sorta - more on that in a second). So wire in your homelink wire on the red with blue wire using a t-tap connector. There won't be an oem place to conveniently install a grounding wire so just drill a small hole in the overheadlight bracket sheetmetal and put a sheetmetal screw. There you will install your crimp-on loop and ground wire.
Now choose your adventure. For the auto dim, ideally you want a true ignition switch on 12v source. The brown wire is switched, but only sort of. The brown wire is a timed constant 12v, so if you use it as your switched source for the auto dim, the mirror will turn off only in the following circumstances: 1) alarm//lock the car 2) 15-20 (?) minutes after leaving the car unlocked 3) manually turn on the overhead lighting 4) every time you open a door. It works without flaw, but it's a bit funky to see your mirror power switch on/off for 30 seconds every time you open the door.
In my universe, that's not the best. So I'd suggest doing a bit more work and tapping into the headlight switch wiring. To do this, take off the left A-pillar trim, using a guide wire/phishing technique, pull wire through the headliner, down the a pillar, down under the dash and use a t-tap on a true 12v switched source there (I think a purple/black wire, 2nd from top left).
Anyways, your final result will be professional and clean.
Reminder: wash your hands thoroughly before messing with headliner and be very gentle when prying. Hope this helps!
Last edited: