Upgrading a car's audio system is one of the most common aftermarket improvements to modern cars, right up there with mufflers and cold air intakes. I'm writing this as a beginner's guide to DIY head unit replacement. This is for informational purposes only. Specific questions may come up that are case dependant. I'm happy to help anyone I can if I can.
There are several factory head units available from Dodge, but the good news is, replacing them is almost a one-size fits all solution. There are two basic types of factory head units in the challenger. Those with a factory amplifier and those without. It just means changing a couple of wire splices. I'll start with a list of Dodge options.
You may have seen these 3 letter codes pop up from time to time. Dodge has a total of 8 head unit's they put into their vehicles. They are:
The "N" denotes a navigation package, and some of these are not available on the challenger from the factory. To my knowledge, the available options are the RHR, RER, RHB, RBZ, REN, and RES depending on year and options. Someone let me know if I'm wrong on that. I'm not an expert on factory options. I never recommend replacing factory with factory. It's super expensive and severely limiting compared to aftermarket. That's going to be the same case for all audio related things. Carmakers usually slap together an audio system as the last step to designing an interior, and of course it's always built by the lowest bidder.
Which head unit you have is not crucial to replacing it with aftermarket. What does matter is if you have a factory amplifier or not. The base 4 speaker system does NOT. The 6, 7, 12, or 18 speaker packages do. Identify what you've got and keep that in your back pocket for later.
To remove your factory head unit from the car the first step I always recommend is to unhook the negative terminal of your battery (in the trunk). This goes for any time you do anything electrical in your car. Just loosen the nut and pry it up gently. Don't let it touch the positive and don't go doing anything stupid like touching the positive yourself when you're also touching the negative. It's easy to do when you've got an 8" flathead in your hand and you'll only make that mistake 5 or 6 times if you're anything like me. It can damage your car's modules and it can stop your heart, so be careful. In the electronics industry the rule of thumb is to put one hand in your pocket at all times, so you can't complete a circuit through your chest. Shorting the terminals with a screwdriver will just give you a nice wakeup and provoke some dancing. Maybe start a small fire. Just be careful around car batteries as a rule. They're perfectly safe with constant vigilance. Also, after making a modification that involves electrical, I like to have a helper nearby. When I reattach the negative terminal I like to have someone near the area where the modification occurred to listen for pops or sparks.
You'll need to remove the center dash bezel. This should be universal for all challengers. For this I'm borrowing some images from MOONDOGNYC's thread on installing a Lockpick because it's perfect for this step:
After you pull this forward, it will expose the 4 screws holding the radio in place.
Simply remove them and slide the radio forward. Don't pull it, there are connections back there !
Some things to note. If you are very conscious of scratches to your interior, you may wish to remove the automatic shifter knob first and lay down a towel on the center console. I put a couple of scratches in mine and I'm not happy about them. These black interiors scratch really easily. The shifter knob in park sort of gets in the way. It's not necessary to remove it, but it gives you more space to work with. Manuals probably won't have this problem, but use your best judgment. A towel is a good idea. Prying the bezel off for the first time may be a little stubborn. I'd recommend a plastic pry tool of some sort. A flathead works, but could scratch things up. A fingernail might work, but be prepared for a nasty hang nail. Also, there are a bunch of connectors for the A/C controls, seat warmers, etc. back there, so don't go yanking it out with those still connected. They're self explanatory to remove. I don't believe any of them are locked on, so just give them a tug from the base until they come free. If one doesn't come with a little force, make sure it doesn't have a locking tab you need to pull out first.
This is also a good time to point out that depending on the aftermarket radio you'll be using, you may need an adapter bracket. Any single DIN radio (the traditional size) will require one. Most double DIN radios will too, but they'll be a different part. I used this one
from Crutchfield for my single DIN. They recommend using this one for a double DIN
. It keeps it looking clean and provides an easy mounting method. The single DIN comes with a little cubby hole too.
You'll also need an antenna adapter. This one should work
, but someone correct me if I'm wrong. It's the one Crutchfield recommends, so I assume it's good to go. I used a universal, but it's big and takes up a lot of space.
All challenger's employ a CANBUS (controller area network BUS) system. This is the skeleton of all the digital information of the car. It communicates with the other systems using this CANBUS standard. That's how your EVIC (on EVIC equipped vehicles) knows what radio station you're currently playing. If you take away a part, the computer pitches a fit, so the first thing to address is how we fool the CANBUS. There are several products out there that do this as most car manufacturers are moving over to the CANBUS standard. I used the PAC RP4-CH11
. It tricks the CANBUS system by telling it everything is alright, retains steering wheel controls for head units with that option (most do now), and passes the radio signal to any factory amplifiers you might have. It's an all-in-one solution that allows you to bypass the need for a dedicated steering wheel control accessory from your aftermarket head unit's manufacturer. This is the CANBUS system being our friend. Since it communicates with the steering wheel controls and head unit already, we just hand it a note from our steering wheel telling the head unit to turn up the volume. The CANBUS acts like UPS and takes the note to the head unit. The CANBUS standard is a great invention and it's not going anywhere.
Now comes the most difficult part of installing an aftermarket head unit, but it's really not that bad. At this point you'll have 4 important wire bundles to deal with. The factory stereo plug, the PAC's main bundle/plug, the head unit's bundle (one side plugs into the head unit, the other gets spliced), and the steering wheel 3.5 mm jack (or 2 wires to be spliced for some aftermarket units).
Splicing wires is easy, but it can take a little time. You'll need a few tools depending on the method you use. The best electrical splice you can make comes from soldering wires together. Soldering is a skill, and beginners will find it intimidating. It requires a soldering iron (about $20-30 for a cheap one at Walmart or Home Depot), and some solder flux designed for electrical use (not plumbing solder). If you know how to do this, you probably don't need this guide. I'll focus on the beginner friendly method using splices. Wire nuts are what your house uses if you've ever changed a light socket or installed a ceiling fan. Wire nuts are not advised in a car environment due to the vibrations and temperature changes of a car, but they do work.
What we want are "butt splices". They look like little hollow cylinders and come in a variety of colors. Lucky for us these colors are standardized. Typically red is used for 20-22 gauge wire, blue for 16-18 gauge, and yellow for 12-14 gauge. For this task, I recommend blue for general splicing, but they'll all work. Red will be a tight fit and won't work for power or ground wires, and yellow will be a little bulky, but might be helpful for power and ground wires (which are thicker). You'll also want some form of protection for your splices. Electrical tape is the most commonly available, but wrapping it around wires when you've got 15 wires nearby can be cumbersome. I recommend heat shrink tubing (available at Walmart or Home Depot). Heat shrink tubing is exactly what it sounds like. You slip it on one side of the wire, make your splice, slide it over that splice, and heat it up with a flame (such as a lighter). It shrinks to fit over the splice and looks real clean.
Splicing should be done inside, away from the car and garage. It'll take you 30 minutes or so, but don't be ashamed if it turns into 2 hours your first time. Remember, this will be installed in your prized posession. What's an extra hour for years of enjoyment. To make the splice, all you have to do is match the wires to their correct counterpart. This will be discussed below in detail. If the wire isn't already pre-stripped you'll need to strip off about 1/2" of the outer jacket to expose the metal underneath. This is easiest with a wire stripper, and I recommend the kind that look like pliers. The more common version to find has the stripper section down toward the handle, and those are cumbersome when you're dealing with 15 other wires nearby. Find the gauge of the wire you're stripping and clamp the stripper on it about 1/2" from the end. Spin it around once to make a clean cut, then slide it toward the end. The outer jacket will slide right off. If you get a stray strand of wire don't sweat it, but try to make sure it ends up in the garbage. If you step on it in just the right way with bare feet it can cut the skin and it gets itchy. Keep a clean work environment.
Now we make the connection. With the wires properly stripped you place each end of the wire you'll be joining inside the cylinder butt splice. Go ahead and slide the heat shrink tubing onto one end and push it down a little bit so it's out of the way. Jam in all the exposed wire you can. Hopefully you don't end up with too much bare metal exposed, but it's not a big deal as long as you've got your heat shrink tubing at the ready. Now grab your pliers or vice grip and crush the tube onto the wires. Crush it good. It's hard to break the plastic butt splice. It's much easier to yank a wire out of a weakly crushed splice and these things need to be solid to withstand a car. Once it's been crushed, give each side a tug. Make sure it doesn't come loose. If it does, no worries, we just redo the butt splice. If one side grabbed and the other didn't, you might have to cut it off, restrip that side, and start over. Once you know you've got a good connection, go ahead and slide the heat shrink over the splice in an even manner and put the lighter near it. It should shrink down and create a firm seal. Try to avoid burning the insulating wire. If you have a particularly short wire that you need to extend, you can use this same method. Just be sure you label it in some way if the colors don't match. It could be years before you're back here.
Now for the connection scheme. The instructions for the PAC harness I recommended isn't the most clear. For a base 4 speaker system you simply match colors. Black goes to black, white goes to white, etc. Typically wires are a solid color to denote positive and striped to denote ground where something needs both a power and ground wire. Otherwise, striped and solid are just used because we run out of colors. Some wires will be unused depending on the aftermarket head unit. For instance, a stereo without any video component to it won't use several of the interface wires. You'll just want to heat shrink those so they don't short out behind the dash.
For a factory amplified system the factory amp only receives 2 channels from the head unit. You WILL lose fader control over the factory amp. That's a feature that the factory head unit controls and it's proprietary, meaning Dodge made things difficult for us by burying that information in the signal. The aftermarket can't develop a work around for it because they can't design specifically for Dodge and their silly design. A factory amplified system is MOSTLY just matching colors, with the exception of the speaker output leads. The "rear" channels are the only ones used by the factory amp. Because aftermarket head units have the most flexibility on the front channels, we'll want to connect the front speaker leads of the head unit to the rear leads of the car. This will allow things like bluetooth and voice commands to work properly on the new head unit (if equipped). Here's a picture showing an overview of what you'll be doing:
And here is a wire by wire connection scheme (factory amplified systems only):
You 4 speaker guys can just match colors and connect all speaker leads to their appropriate color. You probably retain fader control too. Again, not all wires may be applicable for you. It depends on the head unit. Factory amplified folks need to make sure the remote turn on for the amp gets wired. It's usually blue, light blue, or blue/white striped on head units. It's blue and white striped on the PAC harness. It could be labeled REM, Amp Turn On, or something along those lines.
Note that you'll need to select the aftermarket maker of your new head unit on the PAC module. It has a turn dial from 0-9 depending on the manufacturer that is included in the instructions. This translates the CANBUS information using the correct language.
Once you've made all the splices, it's off to the races. Lay the new deck on your towel. Plug the PAC into the stock vehicle harness, then plug the radio's harness into the radio. Plug the antenna adapter into the factory antenna and then into the new head unit. If your new head unit supports steering wheel controls go ahead and plug that little harness into the correct location. Most use a 3.5 mm jack for this and it's going to be labeled something like "wired remote" or "SWC". That goes from the back of the head unit to the PAC module. All the plugs should only fit their designated terminals with the possible exception of the 3.5 mm steering wheel controls. Some head units might have a rear AUX input for iPods etc. so be on the lookout for that. Slide the radio mounted into it's adapter bracket into the dash and screw it down using the 4 screws that came from the stock unit. Reinstall all the connectors from the bezel, but don't reattach the bezel just yet. We want to make sure it's working properly, but we need all those bezel connections hooked up to not piss off the CANBUS. Go ahead and turn the car on and give it a test. Make sure you're getting reception, all functions on the deck work as they should, all speakers are playing, and the steering wheel controls work. If you're good, go ahead and push the bezel back into place and you're done. If you're not good, figure out what's not working and try to troubleshoot the problem. It could be a bad splice, or a plug that's not seated in all the way.
I hope this is helpful for some folks, and please let me know if I've made any mistakes. I'll be happy to correct them. If you have any questions about this write up or car audio in general, let me know. I'm going to try to write up installing amplifiers, speakers, building sub boxes, basic fiberglassing, and some more advanced installation procedures in the coming weeks and months. I'm doing this all step by step myself for my new '11 R/TC, but I've got to do it as my budget allows. I hope to have my system fully installed by January/February of '13.