This is a guide to replacing the factory head unit with an aftermarket single DIN head unit. I used a Kenwood KDC-BT958HD headunit, which has a CD player, HD radio receiver and Bluetooth audio streaming and telephony. The telephony feature requires an external microphone, which complicates the installation. I wanted to keep a clean factory look, so the Bluetooth microphone was installed in the factory location, which is to the left of the instrument panel.
- Kenwood KDC-BT958HD head unit (or other single DIN unit)
- Metra 70-1787 Radio Wiring Harness for VW/Audi Bose Integration 1993-2007
- Metra VW9000 Speaker Harness
- Metra 40-VW12 VW Antenna Adapter
- Factory radio removal tool
- Plastic trim removal tools
- Torx T20 screwdriver
- Soldering iron
- Heat shrink sleeving
- Hot air gun
- Zip ties
- Double-sided foam tape Tweezers
- Needle nose pliers
- Hook tool
- Solid core wire for fishing
- Mechanics gloves
Step 1: Remove Battery Cover
In the frunk, remove the battery cover.
Step 2: Disconnect Battery
Disconnect the negative battery terminal by loosening the nut, and tuck the cable so that it cannot reconnect itself.
Step 3: Remove Factory Radio
Insert radio removal tools and once they have caught, pull to remove the head unit, and slide it out. You may want to put a towel over the gearshift to protect it in case you damage it by pulling out the head unit.
Step 4: Disconnect Radio
Remove antenna by pulling on the plug.
Remove blue/green/yellow colored block by squeezing on release catches on the left and right of the connector.
Remove brown and black blocks by pushing release catch and wiggling out.
The black connector is the power supply. The brown connector connects to the amplifier. The yellow connector (the blue and green ones are not used) is for turning on the amplifier.
The top of the factory head unit contains a diagram that shows how the black and brown terminals are wired.
Step 5: Alarm Connections
This contact is for the alarm. The factory head unit pushes it closed. If the factory unit is removed when the alarm is armed, the alarm sounds.
Step 6: Harnesses
Harnesses: Kenwood (on left) and Metra 70-1787 (on right). I ended up using the RCA plugs from the Metra 70-1787 and the large red connector and using the Metra VW9000 Speaker Connector harness for the other connections.
Step 7: Power and Speaker Harness
Metra VW9000 Speaker Connector harness. This will have the power and RCA plugs wired to it.
Step 8: Amplifier Remote
This is the red connector from the Metra 70-1787 harness. It connects into the car’s blue/green/yellow connector. The pins that you can see are for the amplifier remote on and line level audio. The other end of this connector has a blue/white wire for the amplifier remote and violet, green, white and grey RCA plugs for the line level audio.
We need to remove all the pins except for the blue/white amplifier remote power. Use a needle nose pliers to grasp the pin and while firmly gripping the connector, push the pin so that you can pull it out from the wire end of the connector. You will do this for the violet, green, white and grey pairs of wires that are attached to the RCA plugs.
You will be left with this. Cut the black insulated wires so that you have access to each RCA plug. We will connect these to the Metra VW9000 harness.
Step 9: Wiring Guide
This is the completed harness. It is pretty short so that the slack will fit behind the dashboard and allow the head unit to be pushed home.
I soldered each wire together and used heat shrink tubing to cover the soldered joints and provide structural integrity. I shortened the unused wires from the Kenwood hardness and bound them together with heat shrink. Finally, I used three zip ties to made the entire harness act as one.
Step 10: Testing the Harness
Now is a good time to test the harness. Insert the Metra end into the car and connect the Kenwood harness and the RCA plugs to the back of the head unit. Use the antenna adapter to connect the car antenna to the captive antenna socket attached to the head unit. If you wish, you can plug in the Bluetooth microphone as well.
Once you’ve done this, you can temporarily reconnect the battery. When you turn the ignition to the Accessory or Start position, you should be able to turn on the head unit (by pressing Source). Initially, it will ask if you want to exit Demo mode by pressing the button. You should do so. You can test the head unit functions including Bluetooth telephony if you connected the microphone and everything should work.
Now turn the ignition off and make sure that the dash lights have turned off (odometer, etc.) If necessary, open the door to force this. If your continuous power wire is connected correctly, when you turn the ignition back on, the head unit should not be in demo mode, so test this by switching the ignition on. If you see the Demo mode display again, your continuous and switched +12V wires are swapped. An easy way to remedy this is to use a needle nose pliers to push out the two pins and swap them around.
Now disconnect everything and disconnect the battery (obviously you should do this if you need to reverse the wires as well!)
Step 11: Install Metal Mounting Sleeve
Now you can install the metal mounting sleeve. I highly recommend using gloves since it is razor sharp and it is a very tight fit. Pull the wires through to make sure that they do not get trapped (and sliced) when you push it in.
Use a screwdriver or pry tool to push down the metal tabs, which will prevent the sleeve from coming out.
Step 12: Fish USB Cable Through
The Kenwood unit has a captive rear USB connector on a long cable. This is not a good design since the cable is all bunched up and needs to go somewhere if the head unit is going to fit. You will see from the picture that I removed the cassette holder. In time, I plan to replace this with a storage cubby like the lower one. For now, I am going to place the USB cable in the lower cubby.
Use your solid core fishing wire to get from the back of the head unit down to the cassette holder area.
You can now fish the USB connector through by securely attaching the fishing wire to the USB cable. Because of the bulk of the USB connector, it is easy to get it caught and there are many sharp metal edges so be careful for your hands as well as for the cable. The picture shows the USB connector fished through the cassette holder area
I thought that the lower cubby would fit into the cassette holder area but it does not, so I ended up removing the lower cubby and fishing the USB connector down there. To prepare the lower cubby, I removed the rubber insert and drilled a hole large enough for the USB connector in the read of the cubby. I used the Dremel to make it wide so that the connector would fit. I then pushed the rubber insert back in and used a pair of scissors to create a slit in the rubber. Then I pulled it out again and made additional slits around it to enable the USB connector to go through. The result is a nice clean installation and gets the USB cable out of the way.
Step 13: Final Connections
Final connection time! Connect your harness to the factory wires. Connect the other end of your harness to the head unit. Connect the Bluetooth microphone to the captive connector attached to the head unit. Connect the RCA plugs to the line level outputs of the head unit. Rear Left is green. Rear Right is Violet. Front Left is white. Front Right is grey. There is no subwoofer connection. Connect the antenna to the captive antenna connector attached to the head unit.
Now start pushing the black and red end of the harness so that it goes into the cut out on the left side of the dashboard. Use your fingers to feel this, being careful not to skin them on the mounting sleeve. While you are doing this, you will need to raise the head unit. I suggest that you arrange the captive cables so that they lie across the rear of the head unit. You may also need to pull on the captive USB cable that you fished through so that the head unit does not snag on it.
Align the head unit and start to push it in. If it goes in about a third of the way and then jams, the wiring hardness is not tucked into the recess. Pull it all out and start over. If it goes in about two thirds of the way and then jams, one of the captive connectors is catching on the mounting sleeve. Pull it out and rearrange the captive cables.
I removed the faceplate in order to avoid possible damage to it. Apply pressure to opposite edges of the head unit until it is all the way in. If you do need to remove it, the tools that are supplied go into the sides between the metal sleeve and the outermost plastic of the head unit. I found that I needed to use a needle nose pliers to grab the bottom edge of the plastic and gently pull it out since the removal tool itself was not cutting it.
Step 14: Attach Trim, Faceplate and Reconnect the Battery
You can now push on the trim piece that is supplied with the head unit and reattach the faceplate. You can also reconnect the battery and test operation.