Working through a Nav to Non-Nav headunit and wanted to share some quick info on the reusing the OEM backup camera. I've seen a couple threads sharing partial info, but never a full writeup, so here one is. Quality isn't the best, but it's actually really easy to hookup. I'm using a 9" android unit, but steps below should work with any aftermarket headhunt.
Background info: The GX470 is a criss-crossing web of wires and ECUs. On paper, the easiest way to wire up the backup camera is just to tap into the Television ECU which is located right in the passenger footwell (next to the climate control ECU). I saw a writeup where someone tapped into those wires and I literally can't imagine how. There are 3 plugs on the unit and the one needed for the camera signal is on the furthest back plug. I was pretty positive if i even managed to get the first plug out, I couldn't get it back in. Even more important, there is no play in the cables... so yeah, absolutely not diving into that mess. The plus side is, the camera signal and other things we need can be tapped into elsewhere, so that's what I did instead.
Trigger Signal: The Television ECU and the Navigation ECU both have a 12v "reverse" signal we can tape into. The TV ECU is impossible to get to (see above), so I went for the Navigation ECU which is the absolute easiest ECU in the GX to access. Underneath the front passenger seat, flip the middle carpet covering forward and tada: full access to the Navigation wiring. For my 2004 there are 3 main harnesses. The one I needed was on the side closest to the driver side and I tapped into the black/red wire. To make things easy, I used a Posi-Tap connector. This wire is then run either through the center console or along the doorsill up to the headunit 12v "Reverse In" line.
Camera Signal: First thing to do here is run the RCA cable from the headunit back to the tailgate. Passenger side sills pop off, so just run it along the trough. I'm lazy, so I just tucked it under the carpet/siding edge going through the rear area. When you get to the tailgate, you, you'll to pull up the rear sill plate and pull back the passenger side lower plastic covering (see pic). You'll also want to remove all the tailgate trim too. Routing the cable through the door grommet is the trickiest part of the install. Easiest way I found was to first fish a line from the car-side grommet hole down to the bottom of the trunk area. Once you've got your RCA cable at the car-side grommet hole, now cut a hole in the backside of the grommet and fish the line to the tailgate-side of the grommet. Put an RCA to wire adapter onto the cable and connect the positive and negative leads to the camera loom. I used PosiTaps here too to make it easy. Positive to black wire. Negative to white (the one on the bottom, NOT top). Put it all back together and you're done!
Thoughts for future: Technically, you only need to wire up the positive side to the camera signal for this to work. The negative lead from the RCA can be connected to any ground. This leads to another option which you could be tried, but not sure how it would work out. The positive video signal wire transitions to a shielded cable in the tailgate and continues that way all the way up to the front. The shielding looks like some thick transparent tubing. If you look in the front passenger door sill you can easily see the cable (it's tucked behind the black tabs inboard a little bit. I *think* you might be able to cut into the shielding and tap the positive signal right there. Another thing I want to do in the future is wire the camera to always have power so I can look at it will driving. Just waiting on a 12v to 6v adapter to arrive so I can reroute the power (the top two wires in the wiring connector to the camera).
Camera Quality: OEM camera is definitely not the best, but for ease of install I'm okay with it. I tested out two other cameras from Amazon. The first was very similar in resolution to the OEM camera but with slightly better color. The second (which cost $30) was noticeably better quality. I'd say the difference seemed like going from Standard Definition TV to DVD quality. Both are pretty bad by modern standards though.
Word of Warning: I originally planned to replace the OEM camera with a newer camera. However, to get the camera off, you have to pull out an exterior trim piece on the tailgate. This looked like a huge headache and a high likelihood of problems trying to reinstall. On my GX, the little tabs to remove the trim from the inside had been coated in some black plastic coating. I think the easier option here would just be leaving the OEM camera in place and figuring out a way to secure the new camera nearby. This would mean drilling a hole to run the wire, but I think it'd be a better solution overall.
Photo 1 - Navigation ECU under passenger seat. Bottom middle red/black wire on farthest right connector is the 12v reverse signal.
Photo 2 - Running the wire through the door grommet. Most annoying part of the whole process. I thought maybe I could get better access through the turn signal housing, but that didn't work out.
Photo 3 - New cabling in place! Not shown, a $3 female-to-female RCA adapter.
Photo 4 - Close up of new connections. PosiTaps for the win.
Photo 5 - Final result. Good enough! Next up, front cam
Background info: The GX470 is a criss-crossing web of wires and ECUs. On paper, the easiest way to wire up the backup camera is just to tap into the Television ECU which is located right in the passenger footwell (next to the climate control ECU). I saw a writeup where someone tapped into those wires and I literally can't imagine how. There are 3 plugs on the unit and the one needed for the camera signal is on the furthest back plug. I was pretty positive if i even managed to get the first plug out, I couldn't get it back in. Even more important, there is no play in the cables... so yeah, absolutely not diving into that mess. The plus side is, the camera signal and other things we need can be tapped into elsewhere, so that's what I did instead.
Trigger Signal: The Television ECU and the Navigation ECU both have a 12v "reverse" signal we can tape into. The TV ECU is impossible to get to (see above), so I went for the Navigation ECU which is the absolute easiest ECU in the GX to access. Underneath the front passenger seat, flip the middle carpet covering forward and tada: full access to the Navigation wiring. For my 2004 there are 3 main harnesses. The one I needed was on the side closest to the driver side and I tapped into the black/red wire. To make things easy, I used a Posi-Tap connector. This wire is then run either through the center console or along the doorsill up to the headunit 12v "Reverse In" line.
Camera Signal: First thing to do here is run the RCA cable from the headunit back to the tailgate. Passenger side sills pop off, so just run it along the trough. I'm lazy, so I just tucked it under the carpet/siding edge going through the rear area. When you get to the tailgate, you, you'll to pull up the rear sill plate and pull back the passenger side lower plastic covering (see pic). You'll also want to remove all the tailgate trim too. Routing the cable through the door grommet is the trickiest part of the install. Easiest way I found was to first fish a line from the car-side grommet hole down to the bottom of the trunk area. Once you've got your RCA cable at the car-side grommet hole, now cut a hole in the backside of the grommet and fish the line to the tailgate-side of the grommet. Put an RCA to wire adapter onto the cable and connect the positive and negative leads to the camera loom. I used PosiTaps here too to make it easy. Positive to black wire. Negative to white (the one on the bottom, NOT top). Put it all back together and you're done!
Thoughts for future: Technically, you only need to wire up the positive side to the camera signal for this to work. The negative lead from the RCA can be connected to any ground. This leads to another option which you could be tried, but not sure how it would work out. The positive video signal wire transitions to a shielded cable in the tailgate and continues that way all the way up to the front. The shielding looks like some thick transparent tubing. If you look in the front passenger door sill you can easily see the cable (it's tucked behind the black tabs inboard a little bit. I *think* you might be able to cut into the shielding and tap the positive signal right there. Another thing I want to do in the future is wire the camera to always have power so I can look at it will driving. Just waiting on a 12v to 6v adapter to arrive so I can reroute the power (the top two wires in the wiring connector to the camera).
Camera Quality: OEM camera is definitely not the best, but for ease of install I'm okay with it. I tested out two other cameras from Amazon. The first was very similar in resolution to the OEM camera but with slightly better color. The second (which cost $30) was noticeably better quality. I'd say the difference seemed like going from Standard Definition TV to DVD quality. Both are pretty bad by modern standards though.
Word of Warning: I originally planned to replace the OEM camera with a newer camera. However, to get the camera off, you have to pull out an exterior trim piece on the tailgate. This looked like a huge headache and a high likelihood of problems trying to reinstall. On my GX, the little tabs to remove the trim from the inside had been coated in some black plastic coating. I think the easier option here would just be leaving the OEM camera in place and figuring out a way to secure the new camera nearby. This would mean drilling a hole to run the wire, but I think it'd be a better solution overall.
Photo 1 - Navigation ECU under passenger seat. Bottom middle red/black wire on farthest right connector is the 12v reverse signal.
Photo 2 - Running the wire through the door grommet. Most annoying part of the whole process. I thought maybe I could get better access through the turn signal housing, but that didn't work out.
Photo 3 - New cabling in place! Not shown, a $3 female-to-female RCA adapter.
Photo 4 - Close up of new connections. PosiTaps for the win.
Photo 5 - Final result. Good enough! Next up, front cam
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