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andrewbaru

Adding a reverse camera WITHOUT drilling the boot handle and WITHOUT cutting any OEM wires

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Bear with me on this I've been asked about how my experience with fitting a reverse camera through the cap garnish went

First things first, standard disclaimer, I'm not a qualified mechanic/automotive engineer/automotive electrician, you do this at your own risk and I take no responsibility for you damaging the car, or yourself, or blowing the moon up somehow, or anything bad happens at all in any way shape or form.... this is purely a rough guide carried out on a 2017+ UK spec brz, so please double, triple, quadruple check everything I've said by doing your own research on your own car.

In short, it's pretty easy to do, but I found there are quite a few little odds and ends of knowledge that you just won't know when you start out. So I'm gonna try and mind dump it all here, but this post might take a while and be a bit all over the place and scantily filled in until I can write it all out and put it into sentences that make sense 😄

Things to know before you start, and how to find out: Does you car have an easily accessible reverse signal? Does you car have a cap garnish or do you have a lock?

  •  reverse signal should be on the oem head unit block this may be a 20 or 28pin connector (FWIW, mine's 28pin)
  •  if you have a boot lock, you won't have a cap garnish, but you "could" delock you car and add a cap garnish (I don't know exactly how to do that, sorry). If you don't have a lock, you probably will have a cap garnish, open the boot and look on the right side of the under side of the boot handle, do you see a small hole with a black piece of plastic filling it in? That is the bottom of the cap garnish.

Get an RCA aftermarket camera and wire the trigger wire to the options connector (behind and to the left of the head unit ) with a small fuse (just in case) that you can hide behind the dash cover directly in front of the passenger (most, but not all, videos online will tell you to use the trigger wire to trigger only and wire the power to the reverse light, this would be a MASSIVE fanny on though!)

  • what is an "RCA camera"? Check your after market head unit supports RCA (if it has rear camera support it almost certainly does!)https://en.wikipedia.org/wiki/RCA_connector 250px-Composite-cables.jpg <- an RCA reverse camera will have the yellow connector to go into the back of the head unit
  • to not waste everyone's time, the first really import thing you have to note about the reverse signal wire from the car itself (the wire that tells the car/head unit that the gear lever "is in reverse") - on my car it's actually an orange wire on pin 2 of the 28pin block (the one you pull out of the OEM head unit) ... which I found was called "D12" in the electrics docs I could find online
  • 1458513412_D12(28pinauxSWCrevspdmicspdpark)coloured.png.73865523da20efdacd25f51af118dcd4.png
  • ....and means you don't have to wire the camera to the reverse light or similar, your car may be different or not have this at all(!). This is the REAL intended purpose of the reverse camera's trigger wire, if you don't have an easily accessible reverse signal on your car's connector blocks then there's only 2 options to tell the head unit you are in reverse, 1) splice into the reverse wiring to the gear lever "somewhere/somehow" (personally, I wouldn't do this!), or 2) use the camera trigger wire which sends power to the head unit from the back of the car to the front when the reverse light is on, BUT!!! this is NOT how I wired it. If you can't see a way to tell the head unit the car is in reverse, you can actually install it like I did, but it means you have to manually tell the head unit to flick to the camera, which will quickly get annoying!
  • (Btw, for head units that need a parking brake signal, it was pin 15 above... cos obviously you're not going to just wire it to a chassis ground and have the car appear constantly parked, no no no, you wouldn't do that would you, that'd be really dangerous! no, you definitely wouldn't do that, nope)
  • make sure your head unit's iso block adaptor has the reverse signal pin going to the correct pin on the 28pin block, you may have to use a pin remover to change this (easy to do)
  • https://www.dynamicsounds.co.uk/ctssu004-2-subaru-brz-forester-impreza-xv-steering-wheel-stalk-control-adaptor.html
  • https://www.bassjunkies.com/ctssu004-2.html
  • 1170075398_reverseontheisoharness.thumb.jpg.4744748a014ce83c1ed89edf0242c9c3.jpg
  • you might wanna check the reverse camera's power draw, mine is pretty small, like 75-125mA, I seem to remember the options connector's main fuse isn't very large... but I forget the exact rating

Links on how to wire reverse cameras

  • How you're "supposed" to do it: 
  • How I did it:
    Other videos worth watching:
     

 

The options connector wiring and where to find it... this block was marked as "D29" in the electrics docs I found

op-connector2.jpg.5baebfe4c121141af0462a6b1734fed6.jpg

597029460_D29(6pinoptconnCANLCANHpower)coloured.PNG.30c9b26cdad21015bb0005a7463a4fa4.PNG 

1 - +12V Constant (Battery)
2 - +12V Ground
3 - +12V Switched (Ignition)
4 - Canbus High
5 - Canbus Low
6 - N/C
  • the main consequence of wiring the trigger wire to the options connector and not the reverse light is the camera is permanently on with the ignition (make sure to test your camera doesn't get hot!!! some of the cheap ones apparently do), but this is good if your head unit supports switching to the camera when not in reverse as you effectively get a free digital rear view mirror that's handy if you have a lot of crap in the back or on a very humid day when the back window takes forever to clear
  • and other possible uses (good place to also hardwire a dash cam!)
  • Here's the trick on how I hardwired my reverse camera (and dashcam), I noticed when test fitting my head unit that the iso adaptor harness speaker lead connector actually fitted the options connector! Like so..

2014102758_connectisoblockadaptor.jpg.3e7063499d726fca3a06c443a59faa69.jpg

  • So, the simple trick to get a female connector and make a removable hardwired installation (i.e. no cutting of OEM wires!) is just buy the cheapest similar iso harness and use a cheap pin remover and move the wires around, a hack I couldn't believe that it worked :D
  • What I bought, was this: https://www.halfords.com/technology/car-audio/stereo-fittings/toyota%2Flexus%2Fdaihatsu-iso-harness-adaptor---ct20ty01-581881.html
  • 2018338023_halfordslexusiso.png.653b09b61d53eba49b4be383a5ae44a2.png
  • 1547081275_pinremover.thumb.png.d9b9d8a7d9cb4c11b1b53b326a364e13.png
  • ...and what you do is remove the orange, yellow and black wires from the block I've marked as 2) and remove all the speaker wires from the block marked 1), then push the orange into d29's position 1, yellow into position 2 and black into position 3 (make sure you get the pin positions the right way round for the female connector! so when they slot on the male it's right), and bingo, your own options connector... connector:
  • 987906304_opconnectorconnector.jpeg.c56c888f58f7e1b01094ba36e8535525.jpeg
  • once you've made your own little custom harness you can be as splice/chop happy as you like as it's not the car's own OEM wiring.
  • For good measure I also wired in inline fuses so as not to rely on the car's own fuses (overkill, I know, but lets you use smaller fuses), my dash cam has these:
  • 1048360992_inlineholder.png.0a59f6ba7cbc5535eccce9a1e22e9da7.png
  • My reverse camera draws really small amps so I just used this type:
  • 307725267_inlineholdersmall.thumb.png.056a036bd283d41adec569f52bcdd21c.png
  • make sure you wire the camera's trigger wire to the options connector's 12v ignition (d29 pin 3) NOT the 12v battery main, otherwise the camera will be on 24x7 which is a) pointless b) potentially a bit unsafe and c) will very slowly parasitically drain your battery, and when Subaru is giving you a tiny 45Ah battery from the factory that's definitely not a good idea :D

Run the wiring down the "driver's" side (in the uk ;) ) there is an important reason for this....

  • where to ground the camera, when I had a look there are 4 possible ground points I could see:
  1. in the boot, under the crossmember, under the back window/parcel shelf is a bolt/nut that I've read is chassis grounded, however what you'll quickly find is the nut is factory welded onto the bolt! You could maybe try and put another bolt on underneath and use a crimped ring connector between the two bolts but I just thought it was a bad idea. There is also a fair bit of "other wiring" back there that you could maybe tap into but all of it either a) needed a cut/splice... which immediately ruled it out for me, or b) needed a weird connector block to attach it and piggy back the circuit... again, ruling it out for me. If you are happy to splice wires, this is certainly an easy way to go, but not one I wanted to do.
  2. on the passenger's side (uk spec car) - speaker ground? <- might be a bad idea!
  3. on the driver's side (uk spec car) option 1 - speaker ground? <- might be a bad idea!
  4. on the driver's side (uk spec car) option 2 - main chassis ground strap behind the back driver's side (uk spec car) trim cover just under the tiny window, only seems to be on this side of the car, don't bother trying to partially pry the trim away at the top, imho, you need to remove the whole piece... find the "D" number from the BRZ electrics docs
  • there are videos out there that tell you you don't "need" to ground the camera at all, this is kinda true as the shielding of the cables acts as a ground and the return of circuit will go back through to the headunit and ground through its iso block ground. I didn't like the idea of this and wanted to just return to ground as quickly as possible through a main chassis ground. I'm not sure if grounding through the cable shielding might introduce noise on the picture too... take that with a pinch of salt!

Removing the trim - front to back - be careful to not break push clips or force stuff

  • getting the head unit out
  • foot well, middle, bottom kick panel - you don't necessarily need to remove this, but it's easy to do
  • driver's carpet - not necessary if you want to route cables "over the driver's legs and under the steering wheel" instead - think VERY carefully about this, you DO NOT want wires a) impeding the pedals, b) impeding adjustment of the steering wheel, or c) rubbing and shorting!!!
  • foot well, right side, bottom kick panel where the bonnet release is
  • sill cover plastics
  • the rear seat - yes! you really do have to remove this, it's a lot easier than you'd think though! and yes, it does go back easily and not look crap.
  • rear passenger arm rest - this is a VERY large panel and is scary to remove the first time, but really isn't that bad
  • you "might" want to peel back some of the boot lining around the side of the car - easy to do
  • boot lid OEM wiring grommet
  • boot lid interior felt backing card
  • boot lid exterior garnish handle
  • and finally, the ol' cap garnish

Feeding the wiring into the boot lid

Getting a cap garnish, what it is and why use it instead of drilling the boot handle like all the videos online

  • note: you don't actually need to buy one! I just bought a couple spare in case I screwed up the hole or wanted to change the camera to something that needed a different hole later. Also, I wanted to be able to return the car to factory spec, if necessary.

Drilling the cap garnish

Feeding the wire through the cap garnish and waterproofing it

  • I've found you don't have to go too far over the top with waterproofing, as you are running a wire "up and in" inside an already semi-enclosed space, if you wrap the wiring in a grommet reasonably well the likelihood of water ingress is pretty damn low. 
  • What grommet to buy and how I used it to seal the camera cable (also, give it a little test by filling the inside of the cap garnish with water, it shouldn't leak)

Attaching the camera to the boot - again, without drilling/holes

  • 3M tape is bloody amazing, one year, many power washes and much driving, still going strong. The camera doesn't flop around either.

What camera I used and other possible ones you might want to consider

  • look for wide angle, low light cameras
  • beware of really cheap cameras (heat, water proofing, image quality)
  • you don't really need a camera with infra-red or led lights, the car's own reverse light is pretty good, but if you want to use the camera as a rear view mirror at night it may be a problem
  • NTSC vs PAL cameras, cost/ease of getting one/image quality/refresh rate

Cheap bits and pieces that you might want to buy to make the job easier/tidier

  • trim removal tools - link
  • heat shrink wire covers - link
  • cable clips - link
  • cloth tape (tesa) - link
  • automotive connector block pin removal tool - link

Last little thing: be careful when power washing your car or taking it through an automated wash. If you've sealed the cap garnish well it isn't a problem, but, you may damage the camera itself. So far all has been fine with my set up, but it's worth knowing.

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I just routed my camera through one of the number plate light holes. They're tucked under the boot lid garnish and aren't sealed that well anyway so a thin cable doesn't make the seal any worse. Slight compromise on mine was sticking the camera itself below the boot switch. You can still just about use it but I tend to use the key to open the boot so doesn't bother me. 

Only semi permanent change was splicing to the reverse signal for power, grounded with one of the rear light nuts 

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Each to their own...

But yeah, the number plate light holes aren't very wide and really depends on what sort of camera/wiring/routing/how much wire on show....

Also, this was a lockdown project, so I may have overkilled it a bit... "a bit" 8^D

p.s. If anyone's interested, I added a few links and pictures above, but will add more soon

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