V/A Supplied from where?
Discussion
Turns out that my doors locked LED is fine when swapped with one of the others, it's just not getting enough juice to illuminate when the doors are locked? When the doors are unlocked I'm getting -0.02V and 0A, and when the doors are locked I get a whopping 0.15V and 0A on the positive lead to the LED.
Where does this feed from and why so little? Haven't traced (chased!) all the wiring round my dash to work out where it comes from - anybody know how to fix it? If not I'll probably just use the LED for my "fans on" light instead, I don't tend to lock the doors often anyway.
Waits for Lordgrover to hijack thread
Where does this feed from and why so little? Haven't traced (chased!) all the wiring round my dash to work out where it comes from - anybody know how to fix it? If not I'll probably just use the LED for my "fans on" light instead, I don't tend to lock the doors often anyway.
Waits for Lordgrover to hijack thread
LEDs are unlike bulbs, they have to be wired in series with a current limit of some type. Normally this is simply a resistor but can be a limiting circuit. Typically when a LED is lit at normal brightness you should measure around 1.2v across it and the current will be in the region of 15–20ma (0.015- 0.020A). Because there will be a current limiting part measuring what is going on can be a little confusing. The volt drop will depend on how good your meter is. If you have a Digital one then it will draw very little current and the voltage may appear higher, with a cheaper mechanical meter you may get a different reading. Remember that LEDs have to be the correct way round to work.
Sorry that has probably just added to the confusion and doesn’t really help with the question of where is it fed from.
Sorry that has probably just added to the confusion and doesn’t really help with the question of where is it fed from.
Is this low voltage even the case when the LED is 12V? All of the LED's in my dash are 12V, though I did wonder if this one could be the incorrect spec?
The meter I used was digital but I'll re-measure the current to see if there is anything at all there, however small. I've got some nice new LED's to install (just because the finish on the old ones had rubbed off in places) so I'll measure again when I install them.
Would it be the little central locking module that provides the power to the LED or another circuit from the door solenoids for example?
The meter I used was digital but I'll re-measure the current to see if there is anything at all there, however small. I've got some nice new LED's to install (just because the finish on the old ones had rubbed off in places) so I'll measure again when I install them.
Would it be the little central locking module that provides the power to the LED or another circuit from the door solenoids for example?
Never encountered a 12V LED. All LEDs I have ever seen have a forward volt drop of 1.2v or thereabouts I have however seen an component consisting of an LED with a built in current limiting resistor, maybe that is what you have. If the supply simply has a resistor in line then with the LED removed, with a digital meter on DC Volts you should measure close to the full supply on one wire and the other wire should measure less than a few ohms to chassis. If however there is a current limiting circuit it becomes more difficult to figure out what is going on. Sorry still not a lot of help I know.
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