sealed high beam H4 low beam issues

[Car Addict]

Hello again, I recently upgraded my low beams in my 1991 318is from the stock sealed beams to the H4 low beams from my old e28 535is, FYI they are basically brand new. Now I have an issue when I switch my high beams on, they work fine for about 45 seconds, then the left side (driver's side high beam goes out). I then have one high beam on and if i keep driving with the one high beam it takes about 3 minutes then the right one goes out. When I inspected, after this first happened, I found that I had blown both 7.5 Amp fuses. Now after looking at the wiring diagram for both the e28 and e30 the only difference I found was that the e28 used 8 Amp high beam fuses, would this cause my issue?

Thanks in advance,

Car Addict

[M-technik-3]

Blowing the fuse, sounds like short.

[Car Addict]

That is what i thought i can not figure out where it is though I have gone over the wiring with a fine tooth comb.

The only weird part is how long it takes to blow the fuse if it really is a short. Every short I have come across will blow the fuse almost immediately.

[M-technik-3]

Cross short with some section of wires running will mimic this.

Nothing worse than chasing a short.

They might have upped the amps due to thinner gauge wiring to the headlights.

[Car Addict]

I thought the same thing but according to the schematics both cars have the same gauge wiring and even color.

[Mo Brighta]

low issues

Hello again, I recently upgraded my low beams in my 1991 318is from the stock sealed beams to the H4 low beams from my old e28 535is, FYI they are basically brand new. Now I have an issue when I switch my high beams on, they work fine for about 45 seconds, then the left side (driver's side high beam goes out). I then have one high beam on and if i keep driving with the one high beam it takes about 3 minutes then the right one goes out. When I inspected, after this first happened, I found that I had blown both 7.5 Amp fuses. Now after looking at the wiring diagram for both the e28 and e30 the only difference I found was that the e28 used 8 Amp high beam fuses, would this cause my issue?

Thanks in advance,

Car Addict

I would check two things.

1-- is the pin-out on the H4 bulb the same as with the low beams - i.e.,
are the ground , low feed, and high feed in the same arrangement ???

2-- Is the wattage on the H4 bulb stock or 'overwattage'? these bulbs come with 60/55W standard, but are available with up to 100/130 W filaments, maybe that is what you have and the high current is blowing the fuses...

Good luck!

[Bretts85E30]

fyi i did the h4 swap and the only fix for high beam fuse blow out is putting 10 amp fuses in. i have been running the same 10 amp fuses for the last 8 months not one blow out or wire frying.

[millsamus]

fyi i did the h4 swap and the only fix for high beam fuse blow out is putting 10 amp fuses in. i have been running the same 10 amp fuses for the last 8 months not one blow out or wire frying.

What bulb you recommend for an H4 and H1?