Hey folks, I just finished a fairly long, complex project.
I have had a dashcam
in my car for years now. And I like the peace of mind it affords. I have a one hour commute on a road with lots of traffic and lots of lights. Getting rear-ended by someone following too close is a real possibility. In fact in 2015 there were over 1200 crashes along the road I drive.
So I wanted to convert the rear back-up camera into a recorded Bumper Cam.
I learned that the rear camera is just a analog video camera, the same type used for home security. So I set out to figure out how to record the video from the existing camera.
A word of warning:
This project took lots of research. I had quite a few roadblocks pop-up that I had to work around. I tested everything before installing, and while installing.
This won't be one of my usual how-to guides, more of a log of what I did. If you don't know what your are doing with electronics then this mod is not for you!
First off, the Digital Video Recorder.
The DVR I selected is a high quality mobile DVR from SuperCircuits.com
. I have ordered cameras from SuperCircuits in the past, they have always been high quality and long lasting. They are also located here in Austin and provide great personal service.
These DVRs can be purchased cheaper online, but most of the cheap units I found record at only 320x240 or 640x480. This unit records at 704x576. The rear camera isn't HD anyways so that will be fine.
The DVR itself is simple to use. Just give it power and a SD card and it records away. You can change the quality and frame rate, as well as locally playback video files. Here you can see the DVR, a test camera, and small analog display.
My first road block was trying to get the video from the back of the entertainment unit. See my journal for details on that mis-adventure
After doing research on techinfo.subaru.com
, I determined that the best location to access the video feed was on connector i53. This connector is located behind the bottom corner panel on the passenger side. It is far easier to access than behind the head unit.
Just below connector i53, is connector i195. This connector has +12V accessory power, which I will tap to power the DVR.
I wanted to mount the DVR in the glove box. This way the control buttons would remain accessible from the driver's seat. Issue one was that the power input for the DVR is on the opposite side of the enclosure from the video connectors.
So I opened up the DVR and modified it. I removed one of the audio BNC connectors, as I won't be using the audio anyways. In its place I installed a 5.5x2.1mm power connector. I had the connector from a previous project, but you can buy them at Digikey and Mouser.
Now all the connectors are on the same side.
A couple other items of note about the inside of the DVR: The chrome buttons on the DVR rattle, and so while I had it taken apart I coated the buttons with Plasti Dip. The DVR does have a small lithium ion battery glued to the enclosure, this is to allow it to finish writing the last video to the SD card before shutting down, and to hold the time. While I had it open I also applied hot-glue to all the larger components to help make them more shock resistant.
Next I built myself a single video and power cable. I cut up a triple RCA cable, and soldered in BNC connectors instead. I used the third RCA cable for power.
I then had a male and female BNC jack ready to install into the car. I selected opposite genders so that I could plug the two connectors together and bypass the DVR for troubleshooting, and if I need to uninstall the DVR. This came in handy as you will see later. Another power cable was also cut up and readied to install into the car.
I completely removed the glove box and the panel behind the glove box. It is far easier and safer to work on loose parts then to try working on them while in the car.
The photo above shows the top of the glovebox (it's upside down) and the location where I wanted to mount the DVR.
Unfortunately the left most connector ends up hitting the plastic near the screw hole.
I ended up taking the DVR part again and swapped the connectors around such that the unused audio jack was on the far left.
With the new arrangement the cables line up nicely with the back of the glove-box.
I drilled pilot holes, and then enlarged those using a stepped drill bit. I used a carpenter's knife to bridge the gaps between the hole until I had a single large oblong hole.
The DVR now fits in perfectly. In this position it doesn't hit the glove box door or touch anything inside the glovebox.
With my cable built and the DVR mount ready, I could start the wiring process inside the car. I disconnected the negative battery terminal. In general it's a good idea to do this when messing with any of the electronics.
I disconnected connector i53. I then removed the electrical tape from around the wires. This exposed the shielded cable used to run the video feed.
The purple wire is actually just colored heat-shrink around the cable shield.
The black wire is the camera video feed.
I cut the two wires, and soldered in my replacement BNC cables. Before going further I put everything back together and tested that the video camera still works through the BNC connections.
A piece of advice: When working on car wiring always use solder and heat-shrink. Never use wire cutting taps. Don't use crimp connectors on tiny thin wires. Use electrical tape only to bind wires together, don't use it as a substitute for heat-shrink.
Next up I spliced into the Yellow/Red and Black/Blue wires that travel into connector i195. These are accessory power and ground. Each connection was confirmed with a multimeter before splicing.
These connectors were not cut, instead I made a in-line splice. Do to this you carefully use a wire stripper to cut two spots in the wire sheath (But not the wire!). Then, using a exacto-knife, laterally cut the sheath between the two spots. You then peel the sheath away leaving the wire exposed, but un-damaged. Then you wrap your new wires around and solder. In order to get heat-shrink over the in-line splice I removed the two terminals from the connector and then replaced them.
With everything wired up, I am ready to test the DVR. This is where I ran into another road block.
The 2016 7" Headunit apparently tries to detect if a video camera is present each time it is started. If the head-unit doesn't see a video feed from the camera at boot, it assumes the car has no camera and won't show the rear camera feed when you go into reverse. What was happening is that the video from the DVR takes a few seconds to show up while the DVR boots up. If the head-unit doesn't see this video feed in time it assumes there is no camera.
Sometimes the camera would work, and sometimes it wouldn't. I verified this fact by bypassing the DVR using the BNC connection, and the camera worked every time.
What I needed was a video bypass switch. A two position switch which could toggle the video between "direct from the camera", and "video from the DVR" feeds.
I could have done this with a external switch, wired to the video signals. Instead I came up with a slicker method.
The DVR has a two position power switch. I don't need the DVR to have a power switch, I want it on all the time. So what I did was cut the traces which traveled to the switch, and hardwired the DVR to remain on any time it has power.
I then split the video input signal between the DVR and one leg of the switch. Routed the middle of the switch to the video output connector. Then the last leg was wired to the Video signal from the DVR. This way I can use the switch on the DVR to toggle the output video feed.
As always I tested everything on the bench before taking it back out to the car.
With all the roadblocks out of the way all I needed to do was clean up the cable routing, and mount the DVR.
Here you can see the DVR mounted above the glovebox. I used four screws to hold it in place. I had intended on using 3M tape, but decided against it, tape would probably tear up the soft plastic if you ever tried to remove it.
Here you can see the video menu from the DVR. By default it shows the live video being recorded. I can use the buttons on the DVR to playback any previous recording.
I keep the bypass switch set to "Direct from Camera" mode to ensure the back-up camera is detected by the head-unit at startup.
The rear camera isn't HD, so the video feed isn't good enough to read licence plates. But it does the job. It provides a little bit more peace of mind that if some tailgater runs into me, that I will have video proof that they were following too close.
The project came together very clean in the end. Other than the blinking lights, you can hardly notice the DVR in the glove box.
Also, at some point in the future I will wire up the head-unit so that it can be forced to display the rear-video feed even if the car isn't in reverse.
I have the wiring for that figured out, but it takes time to verify all the connections to ensure it will work.