Installing LED dome light causes alarm to think door is open

As per the title, when I put my new LED festoon bulb into the dome light housing my alarm assumes my doors are open (as I assume the alarm determines this based on whether or not the interior light is on).

Will I need to go buy a multimeter to figure out what sort of resistor will emulate the equivalent resistance of a regular filament-style bulb, or am I going about this the wrong way?

LET THE DISCUSSION COMMENCE.

(My assumption is that the filament bulb has a resistance of x, whereas the LED bulb has a resistance of y, where x>y and I will need to find a resistor which has a resistance of z ohms(?) so that x=y+z?)

 

Your theory sounds plausible(although I have had an LED Festoon installed for about 5 years without any issues with my alarm system).

 

Thanks for the snappy reassurance, Lloyd. I know that there are a many more people without this problem than there are with it (so far I know of myself and a friend of mine who had the same issue with his R33 and LED dome lights - he just swapped back to a regular filament-type light and his issue was alleviated, though). I've had my old filament one in there for a few weeks now and, considering that the rest of my LEDs are in the post at the time of writing this, I figured that now would be a good a time as any to hurry up and git 'r done.

 

Thats the page for the Wiring diagram. EL-64.
So it gets its 12v from the battery thru the 4N connector behind the fuse panel in the footwell.

The word is that LED's should not be installed in parallell unless each has its own resistor. I would assume these are incorporated in the festoon?

Easiest way would be to rig up a seperate switch for the alarm. As it currently is, you have 12v in, knocking it down for each LED with a resistor, and then presumably the alarm is connected after that. So it's seeing bugger all power so can not compute. Maybe you could piggyback wires on the factory door switches and send that to the alarm to make it right.

 

What sort of led bulb assembly is it? I had one in my black zed and it was an actual circuit board with a series of ultra high outputting micro leds. Was a serious piece of kit considering it came in the car.

Mitch is right though that most parallel led installs have a small resister inline with the positive wire to emulate a higher draw.

Wham up a piccy of what sort of unit you've installed and work it from there.

Festoon globes dont have an extra resister, essentially what creates the festoon is enough to create a current draw large enough for circuits to read such drops.

 

This is the piece I have ready to go in. The opposite side is just 4 LED panel things.

(Apologies in advance for the huge picture.)

 

If the door is closed, there is no power (or is it ground) to the interior lights so they do not light up.

If they are not on, it does not really matter how much power they would draw IF they were on, would it ?

 

The type of bulb should make no difference if the correct trigger wire is connected. Where does you alarm get its door signal from and is it positive or negative triggered?

 

If I were to go to the sparky that installed the alarm, what should I ask them? Just where it gets the door signal and polarity of the trigger?

I am not exactly well versed in the whole electrical business...

 

Well yes.

Every zed alarm I have installed (quite a few) I have gotten door signal from a red wire with a white trace on the drivers B pillar. If not I get it from the same colour wire at the interior light relay. This wire goes to earth when a door or the hatch opens.

This wire going to earth, closes the circuit to the interior light which has 12v going to it constantly, turning the light on. This is a negative trigger as its the earth that has the switch on it not the 12V power feed.

If the alarm is hooked up to this wire it doesnt even matter if there is a normal bulb, led bulb or no bulb at all in the interior light as the wire still goes to earth when something opens.

I feel the issue here is not the bulbs but the quality of the alarm installers.

 

That's what I would expect so my guess is either damaged wiring or something in the design of the LED kit is earthing the system when/where it shouldn't be.