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Discussion Starter · #1 ·
Hi all,

I'm replacing (or trying to) the sliding door dome light with a couple of 1W LEDs.

I wired it up - obviously wrongly - and melted the brown earth wire :oops:

So I undid everything and started researching - this post (screenshot below) is pretty much exactly what I did except he blew fuses!!

My question is why did the wire melt instead of blowing fuse #21? I have a 10A fuse in there at the moment - could it be just dodgy or is there something else going on that I'm not getting?

cheers!

191944
 

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Your fuse is way to high to start with.
You need to look at OHM'S law to calculate amperage draw .
You also need to check cable size and ALL connection's.
1W Led should draw very little so for a cable to melt you may have something wrong or cables to small .
 

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Hi all,

I'm replacing (or trying to) the sliding door dome light with a couple of 1W LEDs.

I wired it up - obviously wrongly - and melted the brown earth wire :oops:

So I undid everything and started researching - this post (screenshot below) is pretty much exactly what I did except he blew fuses!!

My question is why did the wire melt instead of blowing fuse #21? I have a 10A fuse in there at the moment - could it be just dodgy or is there something else going on that I'm not getting?

cheers!

View attachment 191944
That diagram is a pile of ****, switched earth is a new one on me.


Everything in that schematic is wrong.

Send me pictures of what you are trying to do, I'll work it out for you.
 

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Discussion Starter · #4 ·
Your fuse is way to high to start with.
You need to look at OHM'S law to calculate amperage draw .
You also need to check cable size and ALL connection's.
1W Led should draw very little so for a cable to melt you may have something wrong or cables to small .
The wires are part of the original harness so I'm assuming that they are fine.

The fuse in question #21 is responsible for "Dome & Luggage Lamps, Clock, Radio, Central Locking System, Multi-Function Indicator, Vanity Mirror, OBD Diagnostic" not just the LED light so that's why it's a higher value i guess.
 

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Discussion Starter · #5 ·
That diagram is a pile of ****, switched earth is a new one on me.


Everything in that schematic is wrong.

Send me pictures of what you are trying to do, I'll work it out for you.
Thanks! What i ended up doing is putting in a 3 way rocker switch - LED positive goes straight to positive, negative goes to middle terminal of switch and permanent earth and switched earth on the other two terminals.

And it works, sort of. Problem is that there are permanently 8v on the switched earth which produces a slight glow in the LED - where they're coming from i have no idea, I've asked the question in another thread.
 

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Full of Cr*p....
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Why do people post when they know nothing about the subject?
@Mike V
The fuse is to protect the WIRING....F.ALL to do with the load.
And you CAN'T use Ohms law for LED lights....they are NOT resistive, they are a current driven semi conductors.
@miloslo
Nothing wrong with the diagram, as long as you know what the connections to the switch are about. (part no 191944 if you hover over it).

Still don't know why the fuse didn't blow...unless someone rewired it to another source (leisure battery?)
 
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