SparkFun Forums 

Where electronics enthusiasts find answers.

Questions &/or issues related to products in the LEDs and Illumination category should be posted in this forum.
In my campervan I have multi-function reverse / indicator lights. I bought these from a hobbyist who supplied the 2 colour LED units and a black box to control it all. It worked for a bit, but now the black box has failed, and blows the fuse. I imagine the black box contains some programmed chip like an arduino. It has a constant power supply, a ground and input / output wires. I would like to rewire my lights without a complex logic controller so it is more reliable.

After some investigation, the three wires coming from the light unit can be wired up to make the unit amber or white. There is a common +ve lead, and depending on which of the two other leads I ground, dictates whether it shows white or amber. My van's wiring harness is wired the other way round. When I indicate, the indicator wire becomes live (+12v), and when I reverse the reverse cable becomes live (+12v). I was wondering if there is an IC that could change this behaviour? I can imagine a simple circuit using transistors, diodes and resistors that should do the job, but I wondered if this is something I could buy off the shelf? I wouldn't know what to start looking for!

Currently I have wired up the lights so they work as indicators, and I've lost the reverse light feature.

Thanks in advance!
Hi npnr.

I'm not aware of anything off the shelf that does this, but the easiest solution I can think of would be to use a pair of relays and switch ground on and off for the LEDs with those. Transistors would work too, but you'd need to solder those to some perfboard to get them working and automotive relays are super common and can be connected too with crimp terminals.

If you don't mind a bit of clicking every now and then, a pair of relays might be the easiest solution.