# Forum: Analog Circuits Adding a switch and LED to a circuit in a car

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Hello,

I have a car and want to add a diy installed camera.

Here is my inspiration:
https://mx5things.blog/2017/06/08/thoughts-on-modifying-cluster-switch-panel/
In Germany where I am from, the cluster switch panel looks like this:
https://i.ebayimg.com/images/g/ePUAAOSw629fmtzk/s-l1600.jpg
I could add a switch to the lower left that looks like this:
https://www.wheelsjoint.com/how-to-use-360-degree-view-monitor-on-mazda-cx-5-cx-30-cx-3-cx-9-mazda3-or-mazda6/
Nice, perfectly OEM like!
So I got a switch and modified the circuit by adding an led and a little
larger resistor (1801) into the empty spot on the circuit because that
was the only one I had available. What could go wrong besides having it
less bright? Well it was working a first but after a little time the led
was off (I suppose the LED was broken). So I soldered another one in...
Same.

OK, maybe I am so bad at soldering smd and maybe I could find a matching
similar Mazda original and I fould it:
https://a.allegroimg.com/s650/119c36/60872d8f4eaba26bd9c3ecf8f831/MAZDA-2-MX5-14-20-PANEL-STEROWANIA-DC2J66170
All 5 buttons I need, and all resistor values are the same a my original
one except the additional led and resistor (1101).
So the only difference to circuit:
https://ssh16blog.files.wordpress.com/2017/06/switch-schematic.jpg
is that there is another led in the another 1101 resistor in one empdy
(N.I.) path.
What happened? The same as before! It worked a short while at the
beginning but it is like before with my diy solution, it went off again!
Only THIS lower left LED? WHY??? The other ones are in parallel and
everything works as before! How can that be???

What type of signal can come from the 2 pins from the car that can
destoy one added led only with the other ones in parallel? I am really
confused and doubting all my electrical knowledge as an engineerer...

OR am I having bad luck AGAIN that only the lower left LED broke?!?! I
am going crazy!

I hope you can help me answering the question.

Thak you very much and kind regards!

PS: I have added a mirrored and turned picure of the backside of my
original board that you can see the path while comparing it with the
other side:
https://ssh16blog.files.wordpress.com/2017/06/cs-pcb.jpg?w=862&h=458

If you need more pictures, I can give you a lot!

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