Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It

Here's the story of my quest to modernize an older car stereo; may you find some inspiration!

Lately, I’ve been rolling around in my Fiat 500 Abarth, listening to the charismatic pop and crackle of the exhaust bounce off Columbus’s buildings. It sounds glorious; I don’t think I’ll ever get sick of that muffler and resonator-free exhaust mated to the back of that 1.4-liter turbo. But a little music would be nice too, which is why I went through the trouble of hacking up my dashboard so a modern audio head unit would fit.

I lied, anyway… Sometimes I do get tired of that exhaust note. Not that’s it’s annoying, it’ll never be annoying, I just want to bump some tunes sometimes. The Fiat 500 Abarth has Bluetooth, right? That means I should be able to make calls and stream audio seamlessly from my phone. Nope! Fiat 500s of this era have Bluetooth calling, but no Bluetooth audio streaming music. What the hell, Fiat? My Chevy Sonic is a year older and has no problem beaming music from my phone through its factory stereo. The Fiat’s USB input sucks too, so don’t ask. I want a new radio, just let me have this.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
The radio only has Romanized alphabet characters, so my K-Pop songs don’t show up on the display. – Image: Kevin Williams

Yet, herein lies the problem: the Fiat 500 is a single-DIN setup; with the radio directly below the center HVAC vents. I would like to get an Apple Carplay equipped head unit, but the stock radio layout limits things.

For those of you who haven’t spent any time car stereo shopping, there are two universal sizes that you’ll see in many older cars: Single-DIN and Double-DIN. DIN stands for Deutsches Institut fur Normung which basically means “German standard” but practically speaking, it means many car stereos are either sized with 50mm x 180mm openings (single-DIN) or twice as tall as that (double-DIN).

Single-DIN is for your standard, rectangle-shaped, you-had-one-in-high-school car radios (MacGruber’s Blaupunkt, anybody?) while double-DINs are fancier. Many current and very modern cars use proprietary stereo systems slickly integrated into their respective dashboards, but up until not that long ago many vehicles worked off the standard. With that context out of the way, let’s get back to my project.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Stock radio, half removed. Image: Kevin Williams

I had two options:

There is a double-DIN conversion kit. This route would give me the most options of CarPlay equipped head units, but, the conversion involves cutting the HVAC tubes to the vent. Kits give you some plastic paddles to reroute the airflow, but the whole setup is intimidating and requires you to cut a part that isn’t easily replaced.  Or, I could get a single-DIN floating-style touchscreen, but that route only has a few viable options:

  • Alpine iLX-F309, which is $1,000 for the head unit alone, is very large and will block the sport button, hazard lights, and air vents anyway.
  • Boss BE10ACP, cheaper than the Alpine, but still has the same issues; far too big for the car, blocking vents buttons I need access to. 
  • There’s a third option, a widescreen, slim-factor Joying unit, but there doesn’t seem to be many English language reviews about it. The handful of reviews I have found have complained about its functionality and quality, and It’s not even clear if the thing’s got CarPlay, which is the whole point of this stereo upgrade.

The head units from the later model Fiat 500s don’t swap in, either. The whole HVAC routing and dash upper half is different than the older cars, and it’s unclear if the newer head unit will play nice with the older car’s CANBUS system. Very possible to spend lots of money on a head unit that will get bricked if I try and use it.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
This dashboard looks similar to mine, but actually it’s considerably different. – Image: Fiat

Screw it, I’m going double DIN, I decided.

I watched a few videos on YouTube to get my bearings about how hard the job would be. It all looked so looked simple, all I had to do was hack a bit of plastic tubing off, then insert the new pieces to reroute the airflow to new vents. The rest of the install looks pretty much the same as any other head unit install. Confident, I started ordering pieces for my new radio.

Choosing a Head Unit

Clueless to the world of aftermarket stereos, I consulted my all-knowing colleague Chris Rosales, what head unit he’d think would be best for me.

“Sony XAV-1000. Hands down. Don’t get anything else.”

Sounds good, the unit reviews well, Sony seems to be a trusted brand, and I like the fact that unit had a volume knob. I went to one of my favorite retailers, Crutchfield Audio, only to see a big red “BACKORDERED” searing right in to my retinas.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It

OK, that’s cool, I’ll just go somewhere else, right? Ha, wrong. Amazon? Out of stock. Best Buy allegedly had one at my local store, but no sales associate seemed interested in helping me find it.

Same story for other units, too. Any cheap head unit that was under say, $350, was out of stock or backordered for the foreseeable future.

Frustrated, and not willing to chance it on some off-brand Amazon “Atoto” stereo, I went to a local car audio installer and asked for options there. Remember when these stores used to be on every corner, back in the 1990s? 

“Yeah, I’m really short on product right now, everyone is,” said the salesman at Columbus Car Audio. Has the global chip shortage affected the supply of aftermarket head units? Maybe.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

After chatting with him for a couple of minutes, he steered me away from the Sony XAV-1000 (which he was out of stock of anyways) into a Kenwood DMX-4707s; claiming its sound quality and interface (and price) was superior to the Sony. Also, I could get the Kenwood unit that day, and walk out of the store with it. Sorry, Chris. 

Ordering Everything Else

Head units need to be wired up; nothing is truly plug ‘n play here, and generally, all of your car’s wiring harnesses to the stereo are proprietary and will need some alteration to work with your new stereo.

Crutchfield’s fitment tool recommended to me everything I needed to remove the old radio, and wire up the new one. I got the new wiring harness, the harness to wire up stock Fiat the steering wheel controls, the tool to remove the old radio, and instructions to get all that crap together.

The new radio fascia comes from Spiral Audio. They come in three colors, but I opted to get the Rubberized black since I already had a Piano Black interior dash piece.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Screenshot: Spiral Audio

About a week later, everything I needed to complete the job had arrived.

Wiring the Harnesses Up

I am very bad at wiring and electronics stuff. When I was in college, I took a few robotics classes that I struggled through – my soldered connections would disintegrate right as my professors went to grade my work. I’m bad at electronic stuff.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
The gang’s all here. – Image: Kevin Williams

Luckily, my roommate, a computer engineer, is not bad at this stuff. He’s been soldiering since he was five years old and loves rebuilding old electronics. Rather than waste my time and get frustrated, I was more than happy to sit back and let him cook.

As I said earlier, an aftermarket head unit needs a wiring harness and a few more doodads to get everything playing nicely together. Crutchfield sent me two things – a pre-wired wiring harness built specifically for my Fiat, and two little boxes that are designed to interact with the car’s computer and keep everything all happy. According to the kit I bought, I should still have use of the already built-in USB and 3.5mm aux-in inputs.

This wiring loom isn’t as complicated as it looks; each wire is color-coded, and most manufacturers use the same colors to represent the same things. Witing the new radio’s harness is really just a matter of matching colors.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin WIlliams

The instructions that Metra sent with the parts aren’t very good. We figured it out, but namely, the wiring for the steering wheel controls wasn’t explained very well, and I didn’t immediately realize that Crutchfield had given me a spare loom for the steering wheel controls that I didn’t need. 

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Don’t make fun of my soldiering! – Image: Kevin Williams

After some twisting, crimping and soldiering, the harness was wired up, and I was ready for the next step.

Cutting Up My Car

Early Fiat 500’s were not designed for double-DIN units. The tubes that feed the vents that blow air into the cabin are directly above the old radio. An aftermarket double-DIN radio won’t fit unless those tubes are altered (the air would be blowing on the back of the unit, too, which isn’t good).

Spiral Audio’s solution is to trim the tubes down, then install some paddles that’ll create a channel that will go to new vents in a custom fascia that can accommodate a double-din head unit. 

It’s intimidating. You’ve only got one shot, these tubes aren’t easily replaceable if you screw up.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

This is the stock opening. See the air vents? I’ve got to fit a stereo twice as tall.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

As you can see, the air vent tubes are too wide, and the new double din cage does not fit.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

The test fitting is very rudimentary, involving a sharpie and pressing the new cage up against the HVAC tubes. After that, it was time to cut.

Video: Kevin Williams

All was well, kind of.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

We cut too much on the left side. The paddle didn’t quite have enough material to rest on, so it kept falling off. A bit of Toyota sealant and some duct tape, and all was fixed, I think.

Finally Installing the Thing

Plugging in the head unit for the first time, the Metra Axxess instructions said I didn’t need to do anything to initialize either the head unit or steering wheel controls. The unit booted up straight away, the sound was good, everything was working properly.

Unfortunately, the head unit itself is not capable of interfacing with the Fiat’s stock USB port, but it can use the regular 3.5mm jack.

Knowing I was finally in the home stretch, I got excited. I had fixed the problems with the Fiat, and I had made the car my own. I had a nice tint, some sexy wheels, and finally a dope radio that worked better than stock. The Kenwood’s touch screen only volume controls I wasn’t too fond of, but I had steering wheel rocker switches that could change that for me… or so I thought.

After all that work, cutting, and wiring, and making sense out of vague manuals, the steering wheel controls didn’t work.

Kenwood radios are capable of doing steering wheel controls, but they only have provisions for one wire. The Metra Axxess Interface’s ASWC-1 is designed to auto-detect and work with any aftermarket radio. 

The steering wheel controls seem to have to be turned into an analog signal for the head unit to interpet it; a singal goes through the regular Fiat loom, and then to the aftermarket loom. That signal goes into a bog-standard 3.5mm headphone jack, and then that information is relayed to the head unit itself. Wild, right?

For some reason, my ASWC-1 box had detected my car’s controls, but my head unit wouldn’t acknowledge the information. The next four hours involved me unplugging, testing, rewiring, and troubleshooting the steering wheel control box that came with my install hardware kit. Had I gotten a defective unit? According to their instructions, my steering wheel control adaptor kit, thought my Kenwood unit, was a Sony head unit. 

After searching online for hours, I stumbled on an older instruction kit from Metra, with a note about Kenwood and JVC Stereos. You can find that by clicking here if you too are questing for the same information.

“While programming your steering wheel controls, please insert a 10k ohm resistor between the stereo receiver and the wiring harness.”

That seemed silly, and wildly out of date. My instructions hadn’t said anything about a bootleg resistor. I was at my wits end, though. I had followed the instructions I had to a tee, and nothing was working.

What’s the worst that could happen? My roommate found some very old resistors he had lying around from when he last went to… RadioShack. Yes, you can still get to a RadioShack without a time machine. Roomie inserted the resistors in the proper place, then I reset the steering wheel control module, and tried again.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

Irritatingly so, it worked. I had wasted nearly all of my day trying stuff out, and the solution was simple this whole time.

The next day, I installed everything. The aftermarket cage needed a few holes drilled in to accommodate my head unit, but that was easy. 

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

The end result looks nice, but it’s kind of a wreck behind the scenes. The wiring is a hot mess behind the head unit. The new HVAC pathways feel completely ad-hoc, and nothing in the back fits as well as I thought it would. I also lost the ability to aim my air vents with this new design.

Installing a Double-DIN Screen in a Car With a Single-DIN Radio Slot Was a Big Pain but Worth It
Image: Kevin Williams

Still, I now have CarPlay and Bluetooth audio, and the head unit itself is much more powerful and takes advantage of my Beats audio system. Would I do this again? Sigh, yeah. There are no other options, and it at least looks good. 

Wish I could aim the vents, though.

Kevin Williams

Kevin WilliamsKevin's been into cars his entire life, anything from the tiny kei cars in Japan, to the maybe not-so-good American barges of the 1980s. He's flipped more than 25 cars, only lost money twice, and has known how to make his dollar stretch as far as it can. If he ain't talking about cars, he's probably snacking on something sweet and cakey. Contact the author here.