960/90 headlight relays?

[Jim760]

all is well so far...nothin blown yet

[s60ben]

Originally Posted by Jim760

all is well so far...nothin blown yet

As long as you keep them relays from "neeeeerrrr" ing then all should probably be well Jim

Arcing, shorts, high resistance's and low voltages will not cause the bulbs to blow...

[Jim760]

Originally Posted by s60ben

As long as you keep them relays from "neeeeerrrr" ing then all should probably be well Jim

Arcing, shorts, high resistance's and low voltages will not cause the bulbs to blow...

before i wentthough all the wiring, the indicator relay was buzzing like an angry wasp when you tryed to signal... the chosen direction would freeze in the on position andthe relay would continueto make that noise.. as for the headlight relay, when i connected the original H4, and activated the lights (full beam especialy) you would hear what i can only describe as somone flicking a spring. your saying that the issues i discovered are not what caused the problem? then why has it gone away?? also, expain tome why none of the fuses have blown with these faults accuring? thats is the big question.

[Nuisance]

The rapid cycling of the relay coupled with the inductive load, and slight capacitive effect of the cabling has caused a voltage increase. Which is what blew your bulbs.

I could go into the electronic theory, but it is very complex in a resonant circuit like this and would fill pages.

Basically it boils down to the relay cycling rapidly against the reactive load creating voltage spikes, as it does so very very rapidly the spikes are close enough together to cause a general voltage increase. Just enough to blow the bulb. (from your description you were probably cycling above 100Hz)

Shorts causing bulb failure are impossible.
Transformers in a DC line are impossible.
Arcing contacts cusing bulb failure are highly unlikely.
2 lives to the bulb causing failure are impossible.

Why was the relay cycling rapidly? Coil trigger voltage too low, probably caused by a bad earth.

Why have the fuses not blown?
Well the fuses only go when their current rating has been exceeded, they haven't a clue what voltage they are working under. You obviously havent exceeded the current capacity of the fuse.
Fuses are not there to protect your bulbs, they are to protect the vehicles wiring from overload.

[Jim760]

Originally Posted by Nuisance

The rapid cycling of the relay coupled with the inductive load, and slight capacitive effect of the cabling has caused a voltage increase. Which is what blew your bulbs.

thank you! so it was the relay making them pop. and i surefound out why!

Originally Posted by Nuisance

Why was the relay cycling rapidly? Coil trigger voltage too low, probably caused by a bad earth.

Why have the fuses not blown?
Well the fuses only go when their current rating has been exceeded, they haven't a clue what voltage they are working under. You obviously havent exceeded the current capacity of the fuse.
Fuses are not there to protect your bulbs, they are to protect the vehicles wiring from overload.

yep as part of my run through of the wires i cleaned every earth pointi found, regardlesswither or not it looked ok. re fuses, i thought that shorting wire would pop the fuse to the relevent circut. i mean there waslive wires eathing to the body.. i would of thought that would of done something
but clearly it did not. i know the fuses wontstopthe bulbs from blowing, asyou say they are to protect the wiring, but with the way things where poping 1st thoughts where "ok somthing is tripping the circut.." but nope!

so yeah, its been bad earths causing the relays to misbehave and in turn, poping bulbs. CASE SOLVED!
thank you.
Jim