Custom Input Jacks

From Fozzee.net

Overview

With my audio input converter on the way and no immediate plans for a Carputer, I figured I should have a way to feed sound from my phone, MP3 player, laptop, etc. I found a discussion on the 'Tex about putting an iPod in one's armrest, and thought that sounded like a good idea. I figured I'd punch a hole in the hub area, as shown, and route both a USB power jack (to be connected to power now, and to the carputer when that's done, as well as an audio input connected directly to the input converter. Eventually, that input would feed the carputer, yielding the same effect. (This would be useful for a friend's MP3 player, or something)

Disassembly

I started tearing into the car by laying both seats clear back, and sliding them as far aft as they'd go. From there, I popped the driver side cover off the armrest, revealing the tilt mechanism. At this point, the whole armrest assembly can be removed by removing the green bolt. The armrest is additionally held in place by two rails (not pictured) and the bolt serves only to hold the rails in contact. Before removing the armrest, I'd recommend releasing the trim from the right side of the armrest, which wraps around both the front and back of the armrest's support base. You wont be able to get it out, but I'm not sure that the armrest will slide free with it in place.

To my surprise, I found that there was a small, oval knockout already in the armrest liner. This seemed about the right size for a USB plug, but it ended up being just the wrong size: too big for the jack alone, and too small for the entire rubber-molded housing. I ended up deciding that the USB plug would go in the side with the knockout, and that I'd drill a 15/64ths hole opposite it, for the 3.5mm headphone plug. The headphone jack mounted without a hitch, though the USB mounting proved a bit tricky.

USB Socket Bracket

I realized that I'd need something to go inside the hub to support the USB socket. It'd need to rotate (with the liner) as the armrest moved, but also be strong enough to take some pushing from the USB cables being plugged in. I measured the hub itself, determining it to be 1-1/8", and fabricated a plastic disc about that size. I then cut a slot in it, just shy of 1/4" and just longer than 1/2", for the USB plug to pass through. One note here: The nylon hub liner has two small protrusions, one at the 12:00 position, and one at the 6:00 position (with the armrest in the "down" position) which may make you believe that your plastic adapter is out of round. It isn't. Just use the force, or tip it slightly as you insert it into the hub. As it ended up, the USB plug wouldn't be long enough to reach through the plastic (about 3/16") and into the socket, so I ended up disassembling a USB extension cable, and passing it through from the front.

To hold the socket in place, I used a bit of super glue on the front (to hold it in place) and applied some "Goop", a rubbery adhesive that I've used to hold the emblem on my wheel bolt covers. I further glued the entire assembly to the back of the liner.

Putting it All Together

While I don't have the armrest back in the car yet, I've played with some "real world" scenarios regarding wear and tear. I've determined that the holes in the armrest (that allow the wire to pass out of the hub) will need enlarged a tiny bit, to make sure that there's no chafing. Additionally, the passenger side hub had no such knockout. The portion of the hub assembly needing notched is nylon, so a round file makes short work of it.

I also discovered that the armrest (along with the liner) rotates well over 90 degrees, while the base remains stationary. (duh) To that end, I've determined that some strain relief is in order. I'm going to be wrapping the cables back around themselves inside the hub, so that the cable can "unwind" as the armrest rotates into the "up" position. I don't raise or lower the armrest often, but it seems like a good precaution anyhow. I've also assured that the side covers fit back on, with the hubs full of connector and wiring. The trim attaches by a plastic ring inside the hub, with indentations that latch onto the protrusions sticking out from the nylon hub liner.

Getting Power

The USB port in the armrest needed power. My custom 5v power supply is hidden inside the center console, directly below the armrest. It's pretty basic, just a 5v fixed regulator, a diode and a filtering cap on a piece of PCB. Most people would power this by splicing the lighter socket, but I wasn't content for that. For one, I was concerned about the constant load. I don't know what sort of open circuit load this regulator has, plus with the device stashed in the armrest, it'd be super easy to forget, and leave your USB toaster oven (No, I'm not aware of a toaster oven for USB (yet). This statement is intended only to make fun of the fact that everything nowadays seems to be USB powered) or something running. So I needed to find ignition-switched power someplace.

I did some research, and decided that I wanted to reuse one of the spare fuse positions in the interior fuse panel, and just run my own circuit. A few notes on the fuse panel: Some positions are always on, some are switched. These two types of positions are "bussed", that is already provided with power. Other positions (especially in the mini-fuse area at the top) are not bussed at all, and have two distinct contacts that can be user-installed. These would be useful for things like remote wires or something, where you don't want just BAT+ connected to one side. Additionally, I can't seem to find the right repair wire for the fuse panel (large or small style). As noted on the 'Tex someplace, p/n 000-979-133-A (the Euroswitch repair wire) is NOT the right one, but will work (sorta) for the larger style fuses. As a sedan, my position 27 (rear wiper) was free, and already bussed to switched power, so I used that.

All in all, this turned out really slick. My only advice for running additional circuits in the panel is to totally remove the steel "knee plate" below the dash, and remove the two screws from the fusebox, so you can maneuver it a bit. Going for the stock fuse position is a ton of work (this took me about an hour, with the load wires already waiting under the dash), but it's totally worth it for that OE look.