BMW Luxury Touring Community banner

1 - 12 of 12 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
My LT keeps blowing the headlight fuse. Stepped up from a 7.5 to 10 amp, didn't help.
Read on another site that the headlight wiring on these bikes is too small.
Replaced the headlight bulb not too long before this started.
Blows it going down the road. Then I have to run on the high beam.
Help...
 

·
Premium Member
Joined
·
3,549 Posts
I'm not familiar with the headlight system starting with 05. I looked up the headlights on line at MAZ BMW. I see that you have a seperate low beam.

In the past, people have had problems with the brown wire that grounds the light. I seem to remember people running a seperate ground for the light that solved their problem.

But, I cannot think of any reason that less than solid ground connection would draw more current? Perhapse the resistance increases through the problem contact?

Just running a temporary ground wire should show is the fuse stops blowing or not.

I'd have to look at the schematic to see if anything else is on the circuit for the fuse that keeps blowing?

In the future consider that changing a fuse to a higher current might be risky? I do not know if the increased risk involves damaging the wiring? If it does, fixing and replacing wires in a wiring harness is a PITA; especially if you aren't around home.

Best from tucson
Bob
 

·
Registered
Joined
·
1,299 Posts
cnhudson said:
My LT keeps blowing the headlight fuse. Stepped up from a 7.5 to 10 amp, didn't help.
Read on another site that the headlight wiring on these bikes is too small.
Replaced the headlight bulb not too long before this started.
Blows it going down the road. Then I have to run on the high beam.
Help...
The magic line is: "Replaced the headlight bulb not too long before this started. "

Was the bulb a direct replacement? Did it draw the same wattage? Double check these items and correct any faults. It could also be an intermittent short in the wiring caused by wires not being in their original position and touching a ground somewhere that it is not supposed to.

Put the original size fuse back in as soon as possible before melting the wiring and find the actual problem. I have a 2000 model and installed the HID system. It draws only 4.5 amps according to the manufacturer.

Robert
 

·
Registered
Joined
·
9 Posts
Discussion Starter #4
The headlight bulb was a direct replacement. I'm going to check the ground wire and ohm the wiring. It didn't start blowing the headlight fuse for a week or two after I'd replaced the bulb. You're the second person that I've seen mention the ground wire and apparently the headlight wires should be larger gauge wires, which is do-able. I've been a mechanic many years and electrical isn't my specialty. Thanks for your help. C.
 

·
Wrencher Extraordinaire
2005 K1200LT
Joined
·
13,922 Posts
Take a good look at the ground wire (Brown) and make sur ethe connection is tight. Then look for rubbing wires. May have pinched one when you put the headlight back cover on.
 

·
Premium Member
Joined
·
1,595 Posts
jzeiler said:
Then look for rubbing wires. May have pinched one when you put the headlight back cover on.
I would think that rubbing wires is your issue. A loose/bad ground would cause a heating issue and might melt something and cause a short but more likely something is rubbing.
 

·
Enjoy The Ride
Joined
·
3,969 Posts
I worked on a bike not to long ago that when the owner replaced the bulb he pinched the positive wire. It didn't blow a fuse but you could smell it.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #8
Anyone have any idea where the brown wire grounds? Is in in front near the small computer or under the back seat?
 

·
Wrencher Extraordinaire
2005 K1200LT
Joined
·
13,922 Posts
All the brown wires make thier way back (through several tie points) to the battery negative. BMW does not use the frame for a ground (but a brown wire does tie into the transmission).
 

·
Registered
Joined
·
594 Posts
1. Change back to original fuse as others have said. Not a good idea try to fix electric problems with bigger fuses...
2. I have had TWICE malfunctioning bulb which has cause fuse blowing (only every now and then). So I really would do immediate scan on the wires and if nothing comes up, would try another bulb before starting to rebuild/-wire anything.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #11
Had a spare bulb I bought when it blew the fuse the first time. Changed it out last night and it appears that was the issue. Never thot a different bulb could draw enough juice to pop the fuse. Drove it last night & today and no problem as yet.
 

·
Premium Member
Joined
·
3,549 Posts
Good news
 
1 - 12 of 12 Posts
Top