Sequential Tail Lights Project

I'm looking into making a sequential tail lights for my car but being bit of a noob on available hardware, i wanted to ask a question.

I'm looking at Relay Shield Module here but i want to know will my tail lights still work (with sequential) without the arduino being turned on or is this arduino dependent?

If not, can you suggest what i can look for? I want to make it where the tail lights will always work without arduino but i can use the arduino inside the car to adjust the timing of the lights.This is mainly for precautions if the arduino were to fail to boot or whatever the reason, and i can still drive without any problems of it being out.

i want to know will my tail lights still work (with sequential) without the arduino being turned on or is this arduino dependent?

You seem to expect the Arduino to make your lights do something, even when powered off. That's like trying to watch a youtube video with your computer turned off.

This is mainly for precautions if the arduino were to fail to boot or whatever the reason, and i can still drive without any problems of it being out.

You should be using a microcontroller that you CAN rely on in the harsh confines of a car, like automobile manufacturers do. Not one that clearly states that it is NOT to be used in anything where reliability and performance must be guaranteed.

PaulS:
You seem to expect the Arduino to make your lights do something, even when powered off. That's like trying to watch a youtube video with your computer turned off.
You should be using a microcontroller that you CAN rely on in the harsh confines of a car, like automobile manufacturers do. Not one that clearly states that it is NOT to be used in anything where reliability and performance must be guaranteed.

What I'm saying is, I expect the relay to work without the arduino but i want the arduino be the component to adjust the timing.

I could use Relay Shield NE555 and manually adjust the timing but I want to adjust the timing inside the car.

You only mention an Arduino and a Relay module.
There's no explanation as to how you intend to connect them to the lights.
(I'm sorry, but I left my crystal ball at the office, so I can't see how you're doing it)

I find a couple of things worrying, though.

  1. As mentioned, an Arduino is generally not designed to live in a car. And definitely not when connected to the wiring there. Voltage pikes there can do nasty things to unprotected electronics.

  2. On any reasonably modern car they have something called a CAN-bus. On some they even use it to detect broken lightbulbs. Overriding the control from the normal switch may make the controller believe the bulb is defect. If your car has an 'bulb out' indicator, this is an issue.

  3. You obviously have no practical experience with car electronics or relays.

  4. Tampering with lights so that they function in a non-maufacturer-approved way can result in the car being declared unfit for the road and yeah... they rip the plates off.

Basically, what you need to do is;

  1. use a set of relay modules and the 'Normally Connected' connections to tie them into the existing wiring loom. If the card isn't powered, the wires will be connected no matter what.
    Then the Arduino(There are 'industrial' versions available) can disconnect the normal wiring loom when ready.
  2. Another set of relays is used, with the 'Normally Open' connections, to connect power to the lights whenever the Arduino decides to.
  3. You'll need sensors to detect the correct clues to act upon.
  4. A big-ass E-stop switch on the dash to power off the contration before getting to a public road.