Metra 70-5521 Radio Wiring Harness for Ford 03-Up Amp

Just bought a ‘04 Lincoln Town Car and didn’t know wether it had an amp/sub or not(couldn’t speak with original owner as it was purchased through a family member and the manual was missing) so I went with this harness because if I didn’t need the amp out harness no big deal, but if I did...well then I’d need it lol. The harness itself is perfect for what it is, a simple harness to prevent cutting and splicing the OEM harness, wires were clearly marked and colors matched the harness for the after market stereo. Went with the Pioneer AVH-X490BS, if you get a pioneer look into getting the parking brake bypass switch. The only problem is that there was nowhere to connect the two blue wires on the harness with the RCA plugs, so I assumed I didn’t need it and just didn’t use it. Reconnected negative terminal on battery and tested radio and it worked great so I figured I was right. I go to install the Infinity Kappa speakers in the rear deck(btw if you have a Town Car be ready to take out the entire rear seat, both bottom and rear cushions to get access to the speakers......) and guess what I see?? A sub and amp.... I was planning on getting an amp for the speakers anyways, and maybe a 8” sub just for a little bass so I’ll just wait to get them rather than hook up the factory amp/sub. If you're replacing a radio you can’t go wrong with Metra, always quality products. Been using them as long as I can remember, and between work, my personal vehicles and friends/family I’ve installed more car stereos and speakers than I can remember and never had an issue with Metra.

I used this harness to upgrade to an aftermarket head unit on my 2005 f250 6.0. Worked flawlessly. My new headunit did not come with steering wheel control functions and says you have to buy the harness for it seperately. You do not. Its a very simple process to retain your functions that i learned about way later. Your upgraded headunit will have a harness included. On that harness it will have a wire labeled "Steering wheel key (+)" and it is orange with a black stripe (atleast on mine) Your stock truck harness will have a blue/red stripe wire on Pin #18 that you must tap into. You dont have to cut it, you can simply military splice it, or use a T-tap to connect the SWK wire on your aftermarket radio harness to connect to your factory harness. Once you connect this SWC(+) wire onto the blue/red wire.. you will be able to setup your functions on your radio. Thats it. One wire. No need to buy the access module or the maestro kit thats around 100 if you have a powerstroke. Hope this helps someone.

Even thought this is labeled for Ford, this was a perfect fit for my 2008 Hyundai Sonata. This item comes with two adapters, I did not need to use the harness with the smaller adapter, I believe this might be to connect an amp which I did not need. I was struggling to find the correct adapter for the 2008 Hyundai Sonata because searching on amazon and google were not leading me to this adapter from Metra since it is labeled for Ford. I came across a youtube video with a guy working on the Hyundai Sonata 2008 and he was using this specific cable model Metra 70-5521 on his stereo. So I decided to order it after searching it up and comparing the adapter to the car's factory adapter. It worked out great because it was a perfect fit. I youtubed enough about the basics of wiring cables together, what the different colors mean, pros and cons of wiring directly to the factory unit wiring (using no adapter). I found videos of others removing the stereo for my specific car (I didnt want to just pry it apart and damage something). Then I went the method of butt connectors to link the wires from this harness to the cables of the stereo unit. The connection quality is strong, the cables from this harness are sturdy so they link well. I used it to adapt an aftermarket radio (BOSS Audio Systems 616UAB single din) using the car's existing factory wiring and connectors. I got the single din install kit (Metra 99-7320). I also got the LeeKooLuu Backup Camera and wired it to the Reverse tail light. I installed this for my girlfriend and it passed her approval test. Everything came together perfectly.

I used this in an '06 Mustang GT. It was easy to wire up, everything was labeled nicely and wiring is good quality. If you have an amp, there are a couple extra items you may need. First is a 12v to 5v voltage converter, this just gets tied into the amp out (blue/white), otherwise you may get popping sounds with On/Off. The second in my case, I needed to add a line out converter from the RCA. This allows me to adjust the gain. Initially I wired this up without it and the sound was terrible, way too much volume sound coming from the amped speakers. I emailed their tech support a few times, they were helpful but ultimately the manufacturer of the head unit I bought recommended the solution. Otherwise it works as intended.

If you’re using this, look into other accessories to retain steering wheel control too. Draw a wiring diagram. Make sure you have everything you need. It works perfectly. Used it to install KENWOOD DDX9707s on a 2010 Lincoln Towncar. Glad I bought it. Make sure you buy butt connectors to connect the harness with your radio/steering wheel control

Picked this up to swap out a malfunctioning head unit from my 2006 Focus ST that was equipped with the audiophile stereo package... the harness for the main head unit was a perfect fit and worked perfectly. the harness for the subwoofer option plugged right in but when it was all said and done the subwoofer was making a LOUD buzzing sound that drowned out music unless you had the volume up way past what I would normally listen to. I fixed this by installing a switch in the "remote line" of the head unit to "turn off" the subwoofer when driving around town with the radio volume down. But that annoyed me more because anytime i was driving anywhere other than the highway (with a lot of road noise) there was literally NO bass on the stereo. Did some research and found that the adapter harness was made incorrectly for my application. there are 8 open spots on the harness connector and my two blue wires (for power and ground) were both on the far left of the connector top and bottom. the blue wire on the bottom was the "system ground" and was in the wrong place. I used a small screw driver to unpin the connector and relocated that wire to the #2 pin position replugged it all in and it works perfectly. Buzz is gone and im finally happy with the install. This ISNT a hard fix at all (i used a tiny screw driver and it took maybe 60 seconds to unpin and slide the wire back into the right port on the connector) but the time it took me to figure it out was kinda crazy. Just a warning that you may have to do this too for your install. Ive included a photo of what the CORRECT pin out should be for the connector... The Connectors pin out is as follows. (as purchased) 1234 1: POWER 2: EMPTY 3: RCA+ 4:RCA - 5678 5: GROUND 6: EMPTY 7: RCA SHIELD 8: RCA SHIELD The CORRECT connector pin out for a 2006 Focus w/ Audiphile Stereo Package is as follows. (as modified in the image) 1234 1: POWER 2: GROUND 3: RCA+ 4: RCA- 5678 5: EMPTY 6: EMPTY 7: EMPTY 8: EMPTY

Great harness

Metra 70-5521 Crutchfield claims this kit does not exist or work on my 07 Mustang with the Shaker 500, and insisted I purchase an expensive PAC kit that requires soldering a diode. With the 70-5521, there are 2 harnesses. The large one is for the main radio harness, the smaller one is for the Shaker 500 subwoofers. You will need a LM7805 or equivalent voltage regulator to convert a 10-15 V signal into a 5V signal. The LM7805CT voltage regulator was needed because the Ford factory Shaker 500 amplifiers require a 5V turn-on signal, while aftermarket receivers use 12V turn-on signals for the amps. This results in a pop or overload of the amp turn-on. The LM7805CT seems to do the trick, and I was told by other Mustang owners not to worry about heatsinks or cooling the regulator because the current/power dissipation isn't that great. I also observed that it was definitely possible to tap into the light/illumination leads for either the message center harness or the HVAC harness to enable the dimming feature on the CX501, but I opted not to touch the factory wiring. The main factory harness does NOT have a power antenna (solid blue), amp turn-on (blue/white) or phone mute (brown) so those must be sealed/wrapped off on the big Metra harness. The smaller Metra harness that goes to the Shaker 500 will have a pair of amp turn-on leads (blue/white) that attach to the OUTPUT side of the LM7805. The INPUT side of the LM7805 goes to the amp turn-on lead coming from the receiver harness. The RCA inputs for the Shaker 500 subs go to the appropriate RCA jacks on the back of the receiver. I soldered all of the ground leads together which goes back to the receiver harness ground lead. I used solder and heatshrink wrapping and can confirm that this wiring kit will work on a 05-09 Mustang (or at least the 2007). Overall: 5/5 stars, very inexpensive, not hard to use, just remember to buy a 5V regulator from Radio Shack - I opted to buy my Fairchild LM7805CT from Digi Key so that I knew I was getting a quality regulator.