This is just a short writeup of what I did to rectify the differences between what classic American car lighting is and what is legally required in the UK for my 1971 Trans Am. This is the short version:
In front:
US classic
amber lights are solid as "daylight running lights" and flash as indicators
UK requirement
white lights for daylight running lights
amber flashing indicators
In rear:
US classic
red tail lights that go bright red as brake lights and flash bright red as indicators
UK requirement
red tail lights that go bright red as brake lights
amber indicators
brake and indicators can't interfere with each other's function
also required is separate bright red "fog" lamps that can be set on with an illuminated switch from the drivers seat
So, for the front part I was pretty pleased to find that you can buy these 1157 LED bulbs that are "switchback LEDs" that are white when on "dim" mode and amber when on "bright" mode. Since my Trans Am has clear front indicator lenses (relying on an amber bulb) the only thing I needed for the front to conform is a pair of these switchback white/amber LEDs.
Oh yeah. You'll also need to stick in some resistors or the flash will be too rapid. The flasher callibrates of the bulb resistance. I put in "LED flasher" units and it still didn't work right until I added the resistors.
The back is more of a challenge. Last time on my old Shelby I went the easy route and just hung extra trailer lights off the rear bumper. But I really didn't want to hack the TA and I definitely didn't want extra lights hanging off or too much wiring butchery.
So, all my challenges are at the back of the car.
My first problem is the need for amber turn signals that aren't brake lights and red brake lights that aren't turn indicators all whilst keeping the original cluster. And my first breakthrough finding was that single colour LEDs have very strong light colour. An amber LED behind an old GM red lens still shines amber! So red/amber switchback LEDs will give me amber indicators but still red taillights. Since I have four taillights I decided the outers should be indicators and the inners should be brake.
The next challenge is wiring (which I'm allergic to by nature anyway). I really wanted to resist much change to the wiring and certainly preferred something clean and reversible. What I decided to do was leave the tail light harness as it was but attach two new bulb holders for the new "brake only" lights. There is an orange and white set of wires going to the brake pedal switch. The orange is power and the white is signal (powered when the pedal is down). I opted to cut this and add weatherpack connectors to it so that it could be reconnected if desired. I then added a new wire from here to the back and ran it into the "high" wire on the two new holders. The "low" and ground wires on the holders I just teed into the existing harness wires for "lights on" and "ground".
Here's the wiring changes. The blue wire is the new one.
This is where I tapped into the brake switch up front
Here's the lefthand new socket with the blue wire coming in for brake and then going over to the other side. The low bulb and earth are teed from the original socket
And here's the righthand side doing pretty much the same
