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DISCUSSION => Electrical => Topic started by: G-Man on November 03, 2010, 09:33:29 PM

Title: High beam headlight fuse keeps blowing
Post by: G-Man 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

Title: High beam headlight fuse keeps blowing
Post by: locknload 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.

Title: High beam headlight fuse keeps blowing
Post by: DesktopDave 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.