Lalai and I recently came upon (cough, cough!) an old-ish used car. Because it is too old, the factory head unit does not have MP3 capability (making this head unit inferior to the one in our Mazda3 back in Manila).
My original idea was to purchase a replacement 2-DIN head unit that had an iPod port and GPS connectivity. Unfortunately, Lalai and I had already bought a TomTom XXL 550 that would be made redundant, the Pioneer DVD/GPS HU is quite expensive, and I would need a replacement dash fascia since the OEM head unit is integrated into the car's dash.
Because of these problems (and the practical one of budget!) I decided to purchase an iPod adapter from Grom Audio, specifically, their iPod/iPhone Adapter V3, which cost US$100 plus under S$20 shipping from the US via ComGateway. They do sell the thing for US$100 but I got it from their e-Bay store for US$90. That's a couple lunches saved right there!
This is how I installed it.
First order of business is to remove the glove box. This is fairly trivial to do (and completely tool-less) and is also required to change the cabin filter.
For the completely hopeless, our friends at Honeywell (proud makers of HEPA filters and similar asthma-friendly gadgets) have this video on replacing the cabin filter:
There are a lot of instructions on the net for installing the Grom (and similar) adapters, such as this one. However, all of these instructions require removing the center cup holder, gear shift, and center console. On all the DIY forums on this topic, there are a few elusive postings who claim that you don't need to remove the center console to install the Grom.
I can confirm, that on right-hand-drive cars it is trivial to plug the OEM HU-to-Grom cable into the back of the Panasonic head unit through the glove box. The Panasonic CD changer port is on the left side of the head unit, next to the FM antenna, and is easily reachable if you have small hands.
However if you have large hands, it's a different story. Same for left-hand-drive cars, where you would need to get at the head unit from the driver's side (no handy glove box to remove).
Here's a photo of the OEM HU-to-Grom cable, already plugged into the head unit, and dangling out of the glove box area.
I decided to sanity-check the setup before closing things up, so I connected everything together and tried playing some music. Everything worked, but here are all the things you would need:
To prevent some nasty accidents if the HU-to-Grom cable gets pulled or jerked, it is a good idea to secure it to one of the many handy wiring harnesses that litter the area. I used some cable ties that I had, you can also use twist-tie wire or tape, but cable ties are neat and easy to remove.
I decided to route the HU-to-Grom cable all the way to the left of the glove compartment gap. There is an A/C duct right under the glove box opening and I decided to double-sided-tape the Grom control box to that duct.
Here's the Grom control box double-sided-taped into place. The 3M tape isn't that strong, but the Grom box is very light, and should never be under mechanical stress anyway.
And another view:
You must ensure that the Grom control box clears the glove box when it closes. My first attempt failed (the edge of the glove box hit the Grom) so I had to waste another piece of 3M double-sided tape and relocated the control box a few millimeters.
You will also want to ensure that none of your cabling efforts block the cabin filter access panel, otherwise you'll have a heck of a time replacing the cabin filter later on.
There are two cables in the iPod/iPhone Adapter Kit: one from the OEM head unit to the Grom control box, and one from the control box to your iPod. I've already noted in the prior photos how to secure the HU-to-adapter cable.
However you must also secure the cable from the adapter to the iPod, so that if the cable gets pulled, it won't pull against the jack on the Grom adapter (that would either detach the box, given the "great strength" of 3M double-sided tape, interrupt the connection, or damage the jack on the adapter).
After securing the cable, place the glove box back into position, and dangle the Grom-to-iPod cable into the glove box.
And voila (ignore the Ambi-Pur air freshener propeller). Total time spent, approximately thirty minutes (including taking photos for posterity). If I had to remove the center console, it would probably take a whole lot longer and with my luck, I'd break some clips on those plastic panels and cause rattles in the car.
Press the "CD" button on the head unit twice to connect to your new CD changer (which is actually the iPod). The steering wheel controls work to control volume and change tracks. The disk-selection buttons on the head unit serve to select one of the first five playlists in your iPod.
If the head unit displays "EX 1" then you can control the iPod directly via its screen, and switch tracks/change volume via the steering wheel controls. If you press disc up/down on the HU, the display changes to "EX 2.. 6" which selects one of the first five playlists that you defined in iTunes. In EX 2-6 modes, you can't control the iPod via its screen.
In all cases, the Grom adapter also keeps your iPod charged up (doesn't work for iPhone 4's due to different charging voltage requirements, I didn't check on the iPad either).