Carputer — wiring
Running the wires around the car turned out to be easier than I thought. First of all, most of them are under the dash. The carputer is installed there right below the radio, the GPS receiver is velcroed up under the dashboard plastic, and so on. The only complicated bits — the rear monitor and the rear video inputs — turned out to be really easy because of how this car is held together.
All the body parts on this van are stuck on like Lego pieces. It’s amazing. I didn’t know how easy these things came off until I had to take ‘em off. Very few screws or bolts. Everything just snaps together. Want a piece off? Grab it and pull. It probably comes right off.
The rubber moulding around the doors and windows holds a lot of pieces on. I was surprised how easily this moulding came off. Grab and pull! And it goes back on really well. No glue, no sticky, no sagging moulding afterwards. It just presses on and stays.
Main cabin wiring
The rear monitor has two audio/video inputs and power. These all go into a distribution module. Then one cable comes out of that module and goes to the monitor. The cable is about 10 feet long, so it made it easy to put the module itself under the dash, behind the glove box. In fact, it’s impressive how perfectly it fit behind the glove box. I ran power to it from the radio, video from the carputer motherboard, and I ran a 2nd set of A/V cables to the rear of the van.
The 2nd set of cables I cut off and soldered to RCA chassis plugs. These I drilled holes for and mounted permanently in the rear interior quarter panel. This panel turned out to be the hardest to get into, partly because it’s so large, and partly because the flip-down rear seat has an axle going through it. I wound up freeing up most of the top half of it and then squeezing my arms behind it to tighten lugs and solder wires. It wasn’t easy, but it only took about 30 minutes.
The cable for the flip-down monitor run along the baseboard under the front passenger door. Then I snaked it up behind the plastic moulding for the door beam. I had to drop the headliner down a few inches to snake the cable above it. This meant removing a screw holding a light assembly in place, but otherwise it was just the moulding and one snap holding it all up.
The A/V cables to the rear run under the 2nd baseboard under the sliding door, then behind that quarter-panel. I couldn’t get that quarter panel removed at first, but once I started pulling the moulding free, it came off relatively easily. The one trick I didn’t see coming was the speaker. The radio speaker is mounted behind a grill that is easily pried off. After you remove the speaker from its housing on the quarter panel, you find a screw securing the quarter panel to the car. Strange location for an anchor, but it was easy enough to find once I decided there was still something hanging on.
The other tricky part here was getting the moulding free around the rear window. I didn’t really want to do it, but it turned out to be necessary. It was easy — once I opened the window — and it went back on easily, too.
Dash wiring
The carputer has wires all over the place, just like a real computer. Here’s a list:
- PSU main power: Comes from the battery, through the firewall, to the PSU
- Power cable: From the power supply, a 20-pin ATX power connector
- PSU control cable: This is the power switch on the computer, controlled by the PSU
- Accessories power: Provides cables to power hard drives, DVD-ROM, etc.
- Keyboard: I ran a keyboard extender cable so I can change keyboards easily later
- Touchscreen/VGA Video: Front monitor, thankfully on one cable
- Rear video output: RCA cable, runs over to the video junction box
- Audio output: goes to the radio AUX input adapter
- AUX Head Unit adapter: carries the audio into the radio (simulates a CD changer)
- USB WiFi antenna: runs up under the dash and rests on the air vents
- GPS Antenna serial/power cable: attached under the dashboard above the air vents
- IDE cables: one out to the hard drive, and one up to the (future) DVD-ROM drive
- Extra USB/Firewire inputs: I plan to mount these on the dash someday. For now, they lie in wait.
All of these cables snake around somewhere behind the front dashboard. The power supply unit (PSU) gets its main power on a 12-gauge wire straight to the battery. It is grounded to the chassis. The PSU itself sits behind a panel next to the driver’s foot.
From the PSU I had about an inch to spare of ATX power cable for the motherboard. It was a much tighter fit than I anticipated. I’m really glad I didn’t have to extend these cables any. There would be at least 22 wires to patch.
The hard drive is mounted near the carputer on a plastic panel that used to be a door. The IDE cable doesn’t have far to go, and the power cable is handy nearby as well. This part I planned.
The DVD-ROM will be mounted just below the radio — someday. For now I have snaked the 2nd IDE cable up there waiting for a mate, idly resting by the USB and Firewire cables. I need to fabricate a mount for all these pieces. I forgot to run power for the DVD-ROM drive. That will be necessary, too.
Someday I may add some more sensory inputs to the carputer. I’d really like to be able to control the carputer from a few more inputs. Specifically…
- The steering wheel has a track-advance button. I’d like to wire that to skip the current MP3 song.
- The radio has FF/Rev, Next/Prev, and Activate outputs. I don’t have access to any of these right now, but I could use all of them to control the carputer playlist. Online docs are hard to find for this.
- I’d like the carputer to begin power-up when the doors are unlocked; this’ll save startup time (30 seconds) but may need a relay or other “logic”.
I’m sure I’ll think of more. That’s the thing about computers… there’s always another peripheral.