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View Full Version : LH low beam headlight keeps blowing a fuse....why?


86mud
19th May 2017, 07:35 AM
HI all

I noticed the LH headlight (low beam only) on my 1998 300Tdi Defender 130 has not been working lately. I first of all thought it was just a loose connection so I tapped the headlight with my hand and the light would came on.

Today it won't come on at all, so I started to check things. Firstly I found that the fuse was blown. Which I thought was strange as I had been tapping the headlight with my hand and it was coming on. So i replaced the fuse with a 10amp and it blew straight away. So I whip out the headlight, check the connection and wiring and all looks good. try another fuse...20 amp and it blows straight away.

So i try the headlight again, this time without the wiring being connected to the headlight bulb. It blows the fuse again.

Where else can I look?

Thanks
Tombie
19th May 2017, 08:06 AM
Starting at the plug - check for any melting of the plug that could bring the contacts together - when you were hitting it to make it work the connections would have been generating heat.

Moving back along the loom look for pinching or melting.
Don 130
19th May 2017, 08:09 AM
It's probably shorting out somewhere, and putting in ever higher value fuses will eventually lead to loom meltdown or fire. Don't do it. A search of the web will reveal ways to fault find safely, or some one with more time than have at the moment may come along and help you further.
Don.
Graekynn
19th May 2017, 08:17 AM
If the short occurs without a globe connected there is a short circuit occurring between the fuse and the globe connector. Can confirm this if both low beam pins have a continuity to ground with the headlight switch off. Cause would either be a short between the low beam wires due to overheating/fatigue or a short to the body from damaged insulation.

If an inspection of the loom is inconclusive, then replacing the wiring from the fuse box to the connector may be the easiest solution. but using a higher than rated fuse to fix the problem can lead to excessive heat build up and more damage to the loom. best of luck!

cheers,
Dave.