Author Topic: High beam headlight fuse keeps blowing  (Read 3747 times)

G-Man

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High beam headlight fuse keeps blowing
« on: November 03, 2010, 09:33:29 PM »
Gang,

I upgraded the headlights on my 91 318i from sealed beams to Hella H1/H4 lights. During the upgrade, I changed the fuses from 7.5 amp to 15 amp. The drivers side high beam keeps blowing a fuse but the passenger side works fine. Any idea of why the fuse keeps blowing for the high beam on one side only?  

G-Man
G-Man
74 2002tii (many mods)
91 318i
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locknload

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High beam headlight fuse keeps blowing
« Reply #1 on: November 07, 2010, 03:23:05 PM »
Does it blow as soon as the lights are turned on, or is it delayed?  could be a short somewahere; try unplugging the bulb and see if it still blows.  Tried switching L&R side bulbs?  Ammeter could prove helpful.

DesktopDave

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High beam headlight fuse keeps blowing
« Reply #2 on: November 07, 2010, 04:06:40 PM »
Might be a short in the H4 pigtail, especially if it blows the fuse as soon as the bulb gets power.  If it takes a little while you might have too much resistance in the stock wiring.  The bulb wattage is the same, isn't it?  Unless you upgraded to 100w bulbs it has to be a short.

+1 on the multimeter...do a continuity test from the bulb to ground with the power off.  Then do a resistance test on the wire.
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