Headlight Fuse Blowing

[mrharris12 32]

Hi all,

 

I have a 418-C and whenever I turn the light switch on in roughly 10 seconds the fuse 15A blows out on it (thats the Amp fuse that should be in according to the diagrams I have).

 

Im assuming it has the factory headlights which are halogen 12v, if so wouldnt turning the lights on blow the fuse since the two headlights and back lights be more than the 15 amps that fuse can handle?

Im not 100% positive if those are the factory lights are not (I am the second owner), and have not tried to disconnect the headlights when turning the switch on which I will do next but came here to confirm what I have is correct.

[ri702bill 8,324]

As @squonk will confirm, it MAY very well be a problem with a bulb itself. Ten seconds is way too long for a fuse to go with a wiring direct to ground short.

[gwest_ca-(File Mod) 11,046]

What is the halogen bulb number you have?

Standard bulbs are 35 watt so about 3 amps each.

[mrharris12 32]

the front headlights are GE H7610 they are 12v 50w

 

 

[gwest_ca-(File Mod) 11,046]

49 minutes ago, mrharris12 said:

the front headlights are GE H7610 they are 12v 50w

 

 

So 2 of them will draw about 8.5 amps.

[mrharris12 32]

so it sounds there is nothing wrong with the lights. Because I am assuming the back lights draw much less

[JoeM 7,874]

 

Some things i have found. 

Try bypassing the switch. Those will go internally bad from time to time. 

I have gotten some fuses that were knock off and they would blow way below the rating. 

Should actually check the wiring for resistance to ground. 

[squonk 41,120]

I have seen fuses blow instantly and some not blow until you exceed the rating by about 5 amps. My best guess is: A you have a wire in the circuit that has a tiny nick in it and it's a small short to ground slightly elevating the amp draw. Or B a bad bulb. You really need a DC Ammeter connected to the circuit itself and measure the amp draw on each bulb individually. If the amps are the same and equal and draw 4 amps apiece the problem is in the wiring or the rear lights. The wire to the rear is known to get chafed on just about every tractor so check that wire where it passes thru panels. If the wire is in a plastic split loom check it good because I have seen the loom itself cut thru wires.

[mrharris12 32]

I disconnected the front headlights and removed the back bulbs and had continuity from the switch to ground with the switch being turned off. So I definitely have a short to ground somewhere. I taped a spot from before that runs over the steering but it might be the wire going to the rear lights, I have looked there at all honestly

[953 nut 55,248]

3 hours ago, JoeM said:

Try bypassing the switch. Those will go internally bad from time to time.

 

1 hour ago, mrharris12 said:

continuity from the switch to ground with the switch being turned off.

I think @JoeM already answered your problem.     Can't hurt to check the rest of the wiring but neither side of your switch should have continuity to ground with the lamps removed.

[WHX?? 48,819]

Lots of time ther can be chaffing on the wiring under the fender pan to the rear lights. I suspect my FEL 520 has that issue. It doesn’t blow till I get rumbling around on her. 

[squonk 41,120]

8 minutes ago, WHX?? said:

Lots of time ther can be chaffing on the wiring under the fender pan to the rear lights. I suspect my FEL 520 has that issue. It doesn’t blow till I get rumbling around on her. 

Quit eating beans and frank's before you use tractor!

[WHX?? 48,819]

2 hours ago, squonk said:

Quit eating beans and frank's before you use tractor!

Yah but @rjg854 says you like the smeĺl... I dunno that's  what he says !

[rjg854 11,362]

   I dunno about all that there     How'd I get brought into this?

[mrharris12 32]

15 hours ago, 953 nut said:

 

I think @JoeM already answered your problem.     Can't hurt to check the rest of the wiring but neither side of your switch should have continuity to ground with the lamps removed.

yeah I think there is a small crack in the wire insulation that is running to the rear lights as Squonk mentioned. Now just have to take it a part a little and see what I see 

[peter lena 8,631]

@mrharris12  wire chaffing , corrosion , cracked connections etc. , are standard stuff , have any alligator clip  test wires ? that last horse I did , with the grass packed / matted corrosion behind the dash was at the top of the class, for  continued issues . also did a RE ROUTE WIRING LAYOUT  once related problems found . like to add screw on wire looms , and use wire wrap , in layout . most important is verify as you go , test / retest  every gain , would also enhance grounding , long setting , original set up , like  bolt on electrical  connections , clean metal , dielectric grease . also a good time to , add a ground wire from battery ground bolt , to engine , RECTIFIER , never count on existing engine tins to carry a ground . amp gauge wakes up . Pete