Car Lighting control system, Design & Build

Not open for further replies.

Thread Starter


Joined Sep 10, 2010
Hi there guys

First off a hello from me. I'm an electrical engineer (studied mechatronics at napier university edinburgh) and now i work in the automotove industry. Most of my time though is more software management and problem solving based now and i enjoy the delights of numerous excel spreadsheets day to day. so, this means a fair amount of my electrical knowledge (if i ever had it) is being steadily washed away with the beautiful vodka lemon and lime i have in my hand. Thats me, so onto the project :eek:

Right the project is not for work its for play. I own a Nissan 350Z and a spend a fair amount of time modifying not only my car but other peoples aswell. There is one modification that I have had in my head for ages that i really want to do... it's a lighting based one. basically i want to build a controller for aftermarket lighting within the vehicle (not chavvy rubbish before those thoughts go any further! :p ) the lighting involves subtle units such as;

-external door handle lights

-footwell lighting
-variation of the colour of the instrument cluster related to revs & other inputs.
-and other general ambient lighting that can be controlled depending on the circumstances.

Why not piggy back these lights onto the existing systems you ask?? simple, I have already attempted this twice and both attempts ended in blowing the body control module (£1k each, expensive mistake :rolleyes: ) the reason for this is that the most appropriate source is the dome lights (map lights) they are the ones that come on when you unlock the car and fade out etc all activated through a variety of inputs. The BCM's were blown by adding a very small extra current draw to them which it obviously wasnt designed for. Normally this isnt a problem as most units in cars are designed with large tolerances but unfortunately nissan chose not to bother here, also the modules have no protection, not even from a short circuit.

Thats the back story as long winded as i have somehow managed to make it there! :rolleyes:

So my initial thoughts for the project scribbled on a bit of scrap paper are

- Need controller
---PIC? (used before)

- Need to be able to source certain signals from the car
---need to avoid CAN based signals! taking them direct from the switches and sensors?
---what kind of conditioning is needed to bring the signals safely into the controller

- need to be able to output to the lighting or anythign else controlled by the controller
---conditioning of the singals from the controller to the devices is needed (transistors, relays)?
---need a number of output pins which will affect controller choice?

power supply
- voltage regulated to protect from power spikes in the car such as starting events
- reverse protected to cope with any faults in the car
- overvoltage protected (preferably to over 24V)
- low voltage, running to at least 9V

Phew! so thats the starting block for the project, the way it looks to me i need to start off by deciding on a controller so if anyone has any suggestions that would be great :)




Joined Apr 5, 2008

Sorry, we can not assist you:

Automotive Guidelines

Guidelines for automotive electronics help

1. Modifications to the ECU or engine sensors are not topics for discussion. Too many safety and legal issues come up. Air quality and safety trump performance.

2. Any homemade wiring modifications to signal or head lighting, or penetrations through the fiewall are not for discussion. The lighting function is to too critical for non-approved wiring and connectors. Many safety issues are involved. Preventing chafing in wires passing through driver-made holes is impossible to guarantee.

3. Add-on items that exist in the passenger spaces is generally okay. Exceptions are lights flashing to music and similar driver distractions. Assurances that the color organ will only get operated while sitting still is not credible.

Each OP should keep in mind the very public nature of these forums. While he may be able to install requested changes in a safe manner, there are others that may be tempted to do the same with no prior experience for guidance or proper tools for the work.

One further constraint to advice/help exists. We are international, but mostly have an audience here in the US. That means that we have to insist that aftermarket equipment must conform with US federal guidelines.

We have to choose a path between withholding all advice for fear of any possible harm, and simple telling anybody everything they wish, as they will only get the information on some other forum anyway. Neither extreme is sensible.
Not open for further replies.