Please help: switched 12V under the bonnet/hood

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Also, there are 4 plugs / connectors which are not connected anywhere - anyone recognize them? 3 of them have 2 wires and 2 with only 1 wire.



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It turned out, those plugs will read 12V if I connect one probe of the DMM to the positive pole of the battery!

What puzzles me is that some of them have 2 pins, and only one shows 12V. However, when I try switching the probe to the negative pole, the other pin of the two, will not read 12V...

I don't know what to think here....

 

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can anyone explain me please how does windscreen washer pump works? I have found a plug with 2 wires under the left headlight, I assume it connects to the washer pump. I read somewhere it has switched 12V, but access is very tight there, so before I go there disconnecting plugs, maybe someone can rule out this route? Or confirm

 

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Not that anyone is reading this, but I have found 3 fuses that have 12V only when the ignition is on - the 3 ones marked with black rectangle on the top - 10A, 15A and 20A.

How does one go about connecting a small wire to a certain fuse?

Will I have to drill a hole for that wire to clear the fuse box cover? How do I keep everything watertight there after my intervention?

Many thanks!

 

[Mark WV]

use an "Add A Fuse" type adapter to borrow power from an active fuse, allows you to keep the original fuse on its intended circuit and add a second fuse for the accessory you are adding. I can't tell if you have space to use this option however.

Amazon product ASIN B007FFG5YI
the old method is just to strip about 1/2 inch of insulation off of a wire, and just insert in under the blade of the existing fuse when reinstalling the fuse. Not as reliable but usually works

to get the wire out of the box, drill a small hole in side of fuse box to exit the wire from the box, and seal with a tad of silicone

 

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Thank you! the height of the piggyback fuse is of concern for me though too. Will try this first as it seems a cleaner option.

Are good with relays? Can you comment on my question if a relay can display unchanged voltage regardless of the ignition? My (very limited) knowledge of the subject says a relay has "to do" something otherwise why use it?

 

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Here is my relay