Long time reader, first time poster.
I've made a custom DIY USB port for my 1983 300d.
Parts needed:
1. Old switch (antenna, rear defrost, sunroof, etc). I got one at the junk yard.
2. USB port from ebay. I bought this one for 9 dlls.
(
HOT Car 2.1A Dual USB Port Socket+Fuse Cell Phone Charger+Audio Input For Toyota | eBay)
3. Wire connectors.
Instructions:
1. Take out the switch from dash. Easiest way is to remove the climate control unit first, then push the switch out from the back. I used the antenna slot as I had previously removed the antenna and don't have a radio in my car.
2. Remove the switch's front cover. Can slide a small flat head screwdriver on the sides and it pops out.
3. Need to remove the back part of the switch. I used a hot soldering iron on the connectors which then fell out with some wiggling. Then used an exacto knife to cut out the remaining pieces of plastic.
4. On the part from ebay, you can also quickly disassemble the switch. You will have a front cover, two usb chips and the plastic casing.
5. I cut the casing in half with a hand saw.
6. Then, with crazy glue I pasted on the half of the casing to the old MB switch with the back part removed.
7. Slide the two usb chips through the front of the newly created casing, threading the wires through the back.
8. Find a 12v wire (hot on switch) and ground wire. I used the ones going to the stock radio. Connect as you would any other electronic mod. The ebay USB port comes with an in-line fuse. Probably want to disconnect the negative terminal from the car battery before doing any electrical work.
9. Insert the casing into the dash opening
10. Put cover on. Didn't look great.
11. Take cover off. Go inside and cut off the lateral edges with an exacto knife.
12. Perfect!!
13. Reverse assemble stereo and climate control.