Golf MK4 Adding a USB Port

Today all mobile phones and most other devices charge from USB ports. We need to have native USB port on our golf mk4.

You can buy some ready ports online but they have some serious limitations.

First of all, you can't install it unless you own a golf mk4 without rear window/seat heating. This is because of the plastic covers of golf mk4 are angled differently on left and right side. On models with seat heating, there are 3 buttons ready in place most left button for left seat heating, most right button for right seat heating and 2nd right button for rear window/mirror heating. So, we are left with 2nd left position to put our USB port. But with all wisdom, manufacturers design those USB ports to go to second right position where the window/mirror heater adjustment button is.

Second reason is, they are ugly! Below is a generic button you can buy online.

We surely do not want to look at this!

Third reason is that these generic USB ports do not support fast charge. We want fast charge when we are charging our phone while driving. Every minute counts!

Requirements:

So, I came up with my own solution to this problem.Needless to say, you need to be able to use a soldering iron and have some experience in wiring up electrical components.

1- I bought the generic model first which has a whole button and holder for the USB ports. I can't use this by itself since the heater button occupies the slot which it goes. But I used the holder part behind the button cover and integrate it into a dummy button.

2- You need to go online and find a 2 port QuickCharge 3.0 (now this is what my phones support, but in future perhaps USB PD) supporting cigarette lighter charger. You need to make sure that it is as small as possible due to space constraints. I went for something like below.

3- You need to have soldering iron, old usb cables, and a grinder.

Instructions:

1- First buy a dummy cover for the port you are going to use.  The model number is 1J0 858 180 C (and other side has same number but B in the end). The best way to check what you need is to remove the existing cover and look under it. Why do you buy one if you have one? Well if you accidentally destroy it, you can have a spare....

2- Now you need to disassemble your USB cigarette socket charger and mark in the middle of the dummy cover where you want the holes. Then you will use the metal piece from one of your old USB cables to melt down the holes. I used the soldering iron to warm up and push through the holes.

3- Unfortunately I forgot to make photos of the following steps. :(

  a) You need to make holes on the sides of the dummy cover so the clips from the USB holder can grab to it.

  b) Then  disassemble the cigarette lighter socket charger and remove the board of it. You need to desolder the springs etc. which form the negative/positive contacts.

  c) I added a red led to mine with a reasonable resistor to dim it so it will blend with other buttons etc. on the dash. I actually attached it to the output of the radio connector's light output which also responds to dimming etc.

4- Now you can assemble everything together and install it in place. Wiring is up to you. Easiest is to connect it to power from the radio connector.

I prepared a custom male/female extension adapter for the which took power from the lighter circuit to get power. The part numbers are 1J0919321 and 357919321 for plastic connector boxes. The numbers to male/female pins are N10319103 and N90732603. These are 4.8mm pins, anything larger won't fit into connector.

I took the ignition status from the radio connector and used a relay which turns on when the key turns on and provides power to the USB port. Without a relay, the cigarette lighter socket provides power constantly. This will cause the port to use 2mA to 10mA (depending on circuitry) constantly. The amount is little, but many such small additions eventually add up. Also, I figure I can use the cigarette lighter socket if I need to charge a device when I am not driving.

But the wiring is all up to you and your skills. Below is photos of the end result. It charges my LeEco phone with Qualcomm processor at about 16W-18W range. Which is plenty if you want to charge your phone quickly. Actually it is so much power that USB cable gets slightly warm.