Melted fuse - not blown, Resistance at fuse box? Options

[FlacaProductions]

Greetings all,

Please excuse the first of what will probably be a small stream of posts as I'm finally with the 914 for a few days so I'm working through a few things.

First item:
I changed out the bulbs in my pilot driving lights that are in the stock positions - put there by a PO or probably Brad Mayeur. I changed them to standard H3 55w lamps but went to a little more blue color to match the LED headlights I have installed along with the spoke works relay to deal with rapid flash and other side effects of the LEDs.

The fog light fuse - 3rd from the right - gets pretty hot and will eventually melt but does not blow.
Could it be as simple as high resistance at the fuse location in the fuse box?

It appears - through trouble shooting - that it only happens when the drivers fog light is installed. if it's not and only the passenger lamp is installed, no issue. Different lamps show the same behavior.

Thanks for the input!

[Spoke]

Try cleaning the fuse ends and the tabs of the fuse panel with a dremel tool. You need to remove any oxidation and crud on the tabs. Contact cleaner will not do it. They must be shiny and free of debris for the best operation.

[FlacaProductions]

Job number one tomorrow. They look really good but from everything I’ve been reading that’s almost always the cause. Everything looks good down at the lights as well. Thank you!

[falcor75]

Are the pilot lights rated for 55W? The stock foglights are only rated at 35W so the extra 20W might be too much for the fuse and old wiring?

[ClayPerrine]

Are the pilot lights rated for 55W? The stock foglights are only rated at 35W so the extra 20W might be too much for the fuse and old wiring?

(IMG:style_emoticons/default/agree.gif)

If you up the wattage on the headlights or the fog lights, you need to add a relay to the circuit. There is a kit available for the headlights on a 911, but all you have to do is add a wire and fuse back to the battery to power it if you use it on a 914.

Zim's headlight kit.

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.allzim.com-1143-1572009216.1.jpeg)

You can do something similar for the fog lights.

Or go to LED bulbs. They actually cut the wattage, and get MUCH brighter. Now you can be as annoying as the new cars.

[FlacaProductions]

This car is new to me since march and came with the Pilots and I assume they came with 55w lamp in them - but I'll check. The only thing I have done on that front is to put the new lamps in them (yesterday - to match the color of the LED headlights) and a couple of months ago, I replaced all fuses as the old ones were...well....old. The fuse box looks clean and I can't see any corrosion, etc. and I've had no other electrical issues.

I'm hoping a good clean will take care of things....stand by....

oh - and @ClayPerrine - I was thinking of just going LED in the Pilots for that reason but couldn't find any H3 lamps that got semi-decent reviews. That actually might be the best answer here - combined with some good fuse box cleaning. Thanks!

[petza914]

Deoxit D5 is much better than regular contact cleaner. It removes oxidation and actually protects the contacts from developing future corrosion. You can get it on amazon. A bunch of us 914 and 928 guys swear by it.

[Spoke]

Here's the basic circuit for the 914 low/high beams and foglights. A single relay is used for the pair of low, high, and foglights so the drive circuit is the same for the low/high beams and the foglights.

The only thing changed is going from 35W fogs to 55W fogs. A 35W foglight burns 2.5A and a 55W foglight burns 4A. Thus changing from 35W to 55W increases the single fuse current from 5A to 8A. That in itself is not significant.

Recall that the fuel pump fuse is 25A so a high current fuse should not be an issue. Running two 55W foglights should not be an issue with a 10A or 15A fuse as long as the fuse holder is clean and the connections are secure. The only improvement that could be made is to use separate fuses for each light like the low/high beams.

[FlacaProductions]

Well - I checked the old tungsten lamps and they are 24w so the new 55s are a significant change I guess. I have cleaned the fuse holder and it is - and was - shiny clean. Could it be the connections on the top side of the fuse box? I’ll check and clean those next - and I have some LED h3s arriving tomorrow. We’ll see if all those changes make an improvement.

Awesome help here!

[FlacaProductions]

Update - the issue seems to have been dealt with by using LED h3 lamps. They are pulling significantly less than the 55w lamps that were melting fuses. It’s interesting as the fuse connections couldn’t be cleaner or shinier but if these work, I’m cool with it. Thanks for all the input.