I am a cheap simpleton that likes to do things right. if anyone else is a cheap simpleton, here's the guide for you. It cost a whopping $182 total for a 5.6" touchscreen to be running in my SLK. ($2.12 after tax for the switch, $3.68 shipped for adapter, and $176 shipped for the head unit)
Here are 10 steps you can do in 5 minutes (literally) to be on the road in style.
What you need:
A Chinese head unit (I recommend the 5.6" touch screen with bluetooth and ipod. It clears the manual shifter and doesnt block anything)
A $2 switch from radioshack
2 wire splicers
an antenna adapter (Metra 40-VW12 was the cheapest I found that worked)
2.5 feet of spare wire
A drill with a bit the same diameter as the switch base
A set of stereo removal keys for stock stereo
a small flat head precision screw driver.
If you want to watch TV, a TV antenna
Wiring harness note:
The Chinese head units all appear to be fitted with the wiring harness needed for our cars already, so no wiring harness is required.
Step 1: First we need to "customize the harness". this takes seconds (literally) by swapping the yellow and red wire. Using the precision screw driver, stick it in the hole above each pin on the pin-side of the wiring harness. slide the wires out the back and swap them. They will click back into place.
Step 1.5: Insert the antenna adapter into the antenna out of the stereo
Step 2: Cut your extra piece of wire in half , and strip all 4 ends. Connect two ends to the switch using either solder, a clip, or ghetto rigged (stuck in and twisted). Some switches also have a self-locking mechanism. Then use electrical tape or shrink tubing to cover up the electrical connections.
Now go out to your car.
Step 3: Drill 2 holes in the glove box on the steering wheel side where there is clearance The SLK seems to be made for it, with plenty of room so there is no wire crunching or accidental button hitting.
Step 4: Insert your two stock removal keys and pull the stereo out. You have to push them all the way in to unlock it. Disconnect all the wires on the back of the stereo.
Step 5:Connect the black side of the harness to the car itself.
Step 6: Stick the switch through the closest to you hole in the glove box, and screw on the back if necessary. Pull the wires through the stereo mounting hole. Using the splices, splice one end to the "brake" wire (usually pink), and one end to the "ground" wire (black).
Step 6.5: Pull the ipod wire through the other hole so your ipod can be in the glove box.
Step 7: slide the metal surround piece off the stereo and into the stereo mounting hole. Put a flat head screw or two in it if you see fit.
Step 8: Pull 3 wires through- the harness for the stereo, the antenna, and the Ipod connection. Connect them to the back of the stereo.
Step 8.5: If your watching TV, also connect your TV antenna at this point and stash it underneith the bracket section.
Step 9: Stick the stereo 1/2 way into the mounting bracket. Put on the faceplate and test it out. If it works, slide the stereo all the way in. if it doesnt work, slide it out and get on SLKworld.com for help.
Step 10: Your stereo is now installed- Connect your bluetooth device, connect your ipod, and set your radio stations- Your good to go! (although you may want to vaccuum up the drill holes!)
Some Q & A:
Does this really only take 5 minutes? yes. It took me approximately 7 but I didn't have the tools together, nor did I think through the switch and such ahead of time.
Why did you put the switch in the glove box? It is against the law in most areas to watch TV/Movies/Etc while driving. The switch allows you to turn off that functionality while you drive.... or you can just not use that functionality, but stereos will automatically prevent you from accessing visual items unless that wire is grounded.
Why did you go with such a cheap stereo? 1 year warranty, and I don't keep cars more than a year. Plus I've bought some chinese stereos before and they worked 6 years + (never had one fail) as long as you get the "better quality" versions. Blue tooth works better than the $2k system in my truck! Lastly, no one knows that but me, it looks like I have a $1k stereo now. Lastly I own so many vehicles, I only put the super expensive stereo in my DD, and with the increases in quality from china, not sure how long I'll even do that.
What about glare? - I made sure I bought a screen with a motorized face plate that allows me to adjust the angles. I think thats important. I also urge you to consider buying an antiglare screen protector. That works wonders in my other vehicles. I typically buy the $1.95 one for the nook color (for some reason seems to be the cheapest) and then simply cut it to size
Are there any hisses or pops or issues with the sound? negative. I heard about these but its significantly better than stock as is. I dont hear any pops, hisses, or hiccups or whatever everyone else complains about.
The stereo appears to cover up the switches- does it? - The stereo is about1" out, so I have no problem seeing or accessing the switches like you may with a 7" screen. I'm also 6'9" tall and 300 lbs, so if I have no trouble with it, I dont see why anyone else would. You dont even notice it because it really doesnt block access at all.
This write-up seems really basic- Why did you waste everyones time on the forum posting it? - Simple, because there were a lot of unanswered questions i had when installign the stereo and I wanted to make sure I helped other people out in my shoes. for example, i bought a wiring harness. I also asked the question "Can aftermarket stereos be installed on these cars" because so many things suggested they couldnt. When it was all said and done, it was the quickest, easiest, best installation I've ever done in my life, and I wanted people to know that.
Hope I could answer some of your questions regardless of what stereo you purchase!