# Update - Melted Plastic on headlight Fuse



## SueandRoger (Apr 14, 2008)

When investigating why my nearside dipped beam was not working I found that the plastic on the10 amp fuse (Correct rating) had started to melt on the side that the power comes into the fuse from the switched supply? The fuse had not blown, but the reason the light had gone out was because the heat generated had not only started to melt the plastic on the fuse but also the plastic around the same side of the fuse holder in the control/fuse box under bonnet of the 2.8 JTD. The exit side of the fuse and wiring to the actual light is not affected (Light still worked). I have checked the plug under the fuse box that supplies the power to the fuses and that appears to be OK. A new fuse box from Fiat is £I40.

I did have a problem with that particular light a couple of years ago when the wiring to the light shorted due to wear on a screw just behind the lamp unit which I repaired and replaced the 10 amp fuse with one from Halfords! and I have had no problem since.

Question is, could the fuse have developed a bad connection which in turn generated the heat or could the problem be in the supply side, fuse box or the wiring from the fuse to the light, if that makes sense? Nothing else is affected, just the fuse that I had originally replaced!

Any advice greatly appreciated and quite happy to bring the camper to someone ‘down South’ for repair if necessary?

UPDATE

Took the camper to Adams Moray in Southampton and their electrician confimed that the loose fuse had caused it to overheat and melt the plastic. So £239 later I have a new control box fitted. The electrician did offer to put a by-pass fuse in but I told him I would 'bite the bullet' and have a new box - no pockets in shrouds!

I also asked for the old control box back as the new one came complete with all the relays and fuses so now I have some spares which hopefully I will never need!

Thanks everyone for your very useful advice.


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## clive1821 (Mar 27, 2010)

the usual case is the the blade fuse holder has become loose and may require bending together and making sure the fuse gose into the holder as a tight fit....if the heat has damaged it to a large digree it may need changing, hope that helps...


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## SueandRoger (Apr 14, 2008)

Thank Clive for your response. What I would like to know is, would a slightly loose fuse holder have caused such heat or could it be something else in the system?

I don't really want to spend that sort of money if it is going to happen again!


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## clive1821 (Mar 27, 2010)

well the head light consumes quite some current and yes if the blade fuse was a little loose in the fuse holder it would start to heat up quite a bit, i have seen this an quite a few cases... look at that first.... if the cable was short circuit to the ground the fuse would blast apart but you have heat hence the advice to look at the fuse holder.... i hope that helps


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## Plankton (Apr 9, 2008)

*Fuse melted*

Hello, another possible cause of melted fuse connections is incorrect wattage bulbs, normal bulbs are 55/60W but 90/100W are available and consume excess current resulting in an overloaded of the circuit.
Frank


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## twinky (Aug 11, 2008)

The melting/heating you describe is caused by a high resistance joint, which as already mentioned, is probably the fuse blade loose in the holder or a rusty connection. 

The fuse is there to protect the circuit in the event of a short so a fault anywhere else would give different symptoms to that youve described. 

If its bad is there a spare unused fuse holder in the fusebox you can move the circuit to rather than spending £140?


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## teemyob (Nov 22, 2005)

*Re: Fuse melted*



Plankton said:


> Hello, another possible cause of melted fuse connections is incorrect wattage bulbs, normal bulbs are 55/60W but 90/100W are available and consume excess current resulting in an overloaded of the circuit.
> Frank


Was going to say the same thing. Also has anything be added on to the same circuit (fogs etc).

TM


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## SueandRoger (Apr 14, 2008)

Thanks all for your help and advice.

I think (Dangerous I know) that I had already made my mind up that it was a faulty fuse holder or possibly that the Halfords fuse was not as good quality as a Fiat one?

The bulb is a 55/60 W and I know nothing has been added to the circuit as I have had the Camper from new.

Twinky, good idea about moving the circuit to a unused fuse holder but I don't know if I have the confidence to do the job as the control box, as Fiat call it, contains the relay for the dipped lights and it is difficult to see which wire goes where as they come via the looms to plug in blocks to the control box. (Does anyone have a wiring diagram?)

I was going to take the Camper to the local Fiat dealer to fix so the cost of labour has not yet been factored in!

Any reasonably close auto electricians out there want some paid work?

Thanks again all for your helpful advice.


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## twinky (Aug 11, 2008)

Could you get to the wires going into the fuse box, cut them out and join them up with something like this?
http://cgi.ebay.co.uk/Inline-Blade-...arts_Vehicles_CarParts_SM&hash=item1e5ca99328

Easier said than done I know 8O especially if its difficult to get to the back of your fusebox.


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## SueandRoger (Apr 14, 2008)

twinky I was wondering if I could do something like that so the link is very helpful thank you. I will check the control box again tonight but from memory I would be able to locate the wire taking the power in to the control box via the fuse but then it goes through the relay internally before coming out to the light!


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## SueandRoger (Apr 14, 2008)

I thought by editing my post it would get a bump - wrong!


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## twinky (Aug 11, 2008)

Nice one Roger.

At least you can be sure its a proper job now. 

You could have had other fuses going the same way.

Money well spent :wink: :wink: .


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## SueandRoger (Apr 14, 2008)

Quite agree twinky, peace and mind and all that! Thanks again for your advice.


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