Checking fuse with multi-meter

Ingwe

Ingwe

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I’m going to hardwire the sat nav in my car having successfully done this in the van. So I was testing fuses for a suitable ‘ignition on’ fuse. Set meter to 20v DC, black wire to a bolt on side of fusebox and used red probe on contact at back of fuse. Found several suitable fuses for hard wiring but I was surprised to see gow many fuses gave no readings whether ignition was on or off.
can these all be spare fuses? I’ve attached a photo and the fuses which gave no reading whether ignition was on or off are on the two left most columns. There were others too in the main body giving no readings. Everything on the car is working so i just don’t understand!
 

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Depends on the spec of the car. The wiring loom and fuses box would be the same for all versions of that model, just more/less active connections dependent on spec, so the spare fuses could be for accessories that you don't have
 
Does the car manual not tell you what fuse controls what
 
Those columns could be triggered by a relay on ignition. If those circuits are not on your spec there may be no relay?

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Just find the radio fuse. That usually works fine. Is there not a fuse diagram somewhere?
Good luck.
 
TCG said:
Does the car manual not tell you what fuse controls what
Click to expand...
I don't have the manual here, locked down in France. Manual back at home. Service record and little manual kept in car doesn't show fuse board.
 
Ingwe said:
I don't have the manual here, locked down in France. Manual back at home. Service record and little manual kept in car doesn't show fuse board.
Click to expand...
What make and model is it?

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Audi A4 2.4 v6 saloon 1998.
 
Last edited:
Thank you ryan_flea- that's brilliant. And it shows that there are quite a number of unused spaces. Quite surprised to see how high an ampage required for fuse37 radio!
 
Can I ask a probably daft question; my car doesn't have a sun roof but fuse 30, which covers this has a fuse in it. Do you think I could just use one of the fuses (piggy backed) or fuse spaces to currently being used?

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Would hazard a guess that you need a switch for the sunroof you haven't got to make the circuit live.
 
TerryL said:
Would hazard a guess that you need a switch for the sunroof you haven't got to make the circuit live.
Click to expand...
That makes perfect sense. I'm minded to use the radio one ( as others have suggested) but just wondered about the spare places.
 
Just seen earlier reply with the same info.
Hope you get sorted.
 
I wired mine to the interior light as the door pins earth the light.
Wasn't thinking straight as I then I found the interior light is live up to the point the doors are locked.
Not a problem for the satnag as that's removed when not in use but the dash cam is also wired to it which means the camera is recording when stationary and unoccupied but not locked.... Servicing etc

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