Driving Lights - Blowing Fuse F4 All The Time

[Dream Weaver 2]

I recently fitted some new driving lights and on initial testing only 1 was working, then they both went out. I left them alone, but as its MOT time tomorrow I've been fixing the little niggles tonight.

 

I know the driving lights aren't needed for MOT but I'd like them to work.

 

However, as soon as I switch main beam on, the fuse F4 on the fuse board, blows immediately. I tried higher ratings right up to 30A but they still blow. Main beam still works fine after the fuse blows, but the driving lights don't work.

 

This is on std halogen lights btw, HIDS are disconnected for the moment.

[Rob_the_Sparky 9]

Time to look for your short circuit! Putting in a bigger fuse is not a bright idea, 30A x 12V = 360W and you are more likely to have 14V so more like 420W. There is no way your lights should be drawing anything like that sort of power so you clearly have a fault.

 

If you blow a fuse it is for a good reson, especially if it blows very quickly. If running close to or just over the rating they blow quite slowly. To take a fuse out fast takes a LOT of current. A bigger fuse may just result in melted wires before it blows.

[Super Josh 4]

Simon, have you got a multimeter? or one you can borrow?

Then you can start unplugging each light in turn and measure the resistance of the circuit. You'll soon find out where the problem is.

 

 

Josh

Edited May 24, 2007 by Super Josh

[Scottieb 0]

Putting in a bigger fuse is not a bright idea,

 

If you' excuse the pun!

[Rob_the_Sparky 9]

Depends where the short is whether removing bulbs helps or not but yes a multimeter is the way foward.

[Dream Weaver 2]

I have a multimeter here, but I'm not overly clued up on what to test.

 

So am I testing across the terminal for each driving light, or further up the circuit? And am I testing for volts or ohms (resistance). If ohms, then what should I look for?

 

And on the subject of fuses, anyone any idea what the fan should be fused at - it was 10A but that blows as well after a couple of months usage - its wired straight through the Emerald rather than std Pug loom.