How to Wire a Low Cost Double Din Head Unit with Back-up Camera: Carzin and More

     I agreed to wire up and install my friend's new Carzin double din head unit. I was amazed at the many features packed into this unit for just $60. This post will cover details helpful to someone installing and wiring such a unit.

     Unbox the unit and familiarize yourself with the parts which include:
1) The seven inch touchscreen head unit. Note the volume, power and aux ports on the left side of the front. Also included is a micro usb jack. On the back are RCA jacks for the camera input and AV out as well as an antenna jack.
2) Two wiring harnesses that plug into the back of the head unit. One is for power and control. The other is for the speakers. These will connect to a wiring adapter that matches the factory harness.
3) Back up camera with wiring.
4) wiring harness to go from camera to back-up light
5) Wiring harness that goes from back-up light and camera to the head unit
6) Remote control

    If desired test the unit before install. First wire the head unit for power. You will need a 12VDC power source. I used a small lead acid battery. Two alligator clip test leads will be needed. Connect the yellow (A4) and the red (A7) to the positive terminal on the battery, Connect the black wire (A8) to the negative terminal on the battery

   

Power wiring complete

Next wire in the back-up camera. To simulate the back up signal we will use another jumper wire. Plug the shorter black RCA cable to the red RCA jack on the camera. The red wire at the other end will need to go to +12V on the battery. The black wire will connect to battery negative although for testing purposes it is not needed.

     Wire the long cable into the back of the head unit. Plug the RCA plug into the cam-in jack on the back of the head unit. Wire the open red lead on the cable to the gray wire on the power jack.

That red wire above goes to A2 (gray in this case)

    Wire the unit to the car wiring adapter 
1) Generally the A12V, ignition 12V and ground should be yellow, red and black respectively, on both plug A and the  car wiring adapter. Others may vary . Refer to the instructions  that came with the adapter. The only other wire I used was the blue (A5, antenna) wire. When I connected the orange (A3, key or steering wheel control) wire the unit would not power up, so I left it unwired. Use whatever means you prefer. I have no trouble with wire nuts as long as electrical tape is used. Others may prefer crimp connections or solder.

Colors may vary on your unit. Mine even varied from the instructions...

...

....for example I have no brown/black wire for A3 (key/steering wheel)

 2) The speaker wires matched up in color from the B harness to the car adapter.
     

Wiring and mounting in the vehicle

     I found mounting the head unit problematic in a 2004 Saturn Ion. It would not fit in the frame of the Metra GM kit that the owner purchased. I ended up mounting it with no frame, using only the two brackets provided in the Metra kit. 

1) Plug the long yellow camera video cable into the head unit and wire the red wire to the gray wire (A2). Find a route to feed the long wire through the dash to an entry point under the door jambs along the left side of the car. 

2) Plug in the wiring harness from the head unit into the factory harness. 

3) Plug the antenna wire into the head unit.

4) Mount the head unit.  

It was a struggle to mount this in a 2004 Saturn Ion

5) Run the long cable from the head unit to the trunk. This is often the most challenging part of the install. Running the wire under the door jambs works best.

Tuck the cable under the door jamb plastic cover 

6) Physically install the camera using the license plate mount. This will vary from vehicle to vehicle

It was easy to drill two holes in the composite material in the Saturn 

7) Find a route for the wiring to one of the back-up lights. This may involve removing a plug and routing along with other wires.

8) Plug the power back-up light cable (black) to the red jack from the camera and route to the back up wiring. Plug the two yellow jacks together.

9) Separate the red and black power wires and splice the two red leads together. Take care if using an automotive type splice. These wires are a very light 22 gauge and those splices are 16 or 18.

Automotive splice seemed like a good idea...

...but the wire was too small, so I went with this

10) Find the back-up power wire at one of the tail lights. There are several ways to locate this wire. One would be to turn the ignition on (do not start). Engage the parking brake or block a tire and shift car into reverse. Now use a automotive test light and probe the wires until the light comes on.  This is the 12V back-up wire. A second way would be to use an ohm meter to find the ground wire. Place one meter lead on a known good ground and the other on one of the two wires going to the back-up light. The wire with low resistance is the ground which also identifies the other wire as 12V.  

11) Wire the power wires to the back-up light. The red wire goes to to back-up 12V.  The black wire goes to the back-up ground wire. There are several ways to do this. If using a splice connector take care. The kit wires are 22 gauge and may not make good contact if the splices are too large. Stripping a bit of insulation and soldering is more reliable. Otherwise cut, strip and use a crimp fitting.

Automotive splice worked here 

12) Test the unit

Not a flawless fit but usable lol