dim headlight

[yamahansolo]

what would cause my headlight to be dim and when you hit the brake light the headlight brightens? do you think the headlight is not getting enough juice and when the brake is applied it sends more juice. i have looked at the fuse box a couple of times and everything looks good. the po did a fuse box mod but it's pretty much the same as stock. i beleive the two thicker brown wires are the tail lights correct? and i know the headlight is the red one with the yellow stripe. and the mains are the two thicker red ones. i must be missing something somewhere. i wonder if the wire comming from the stator for the lights is going bad? i know on my old xs750 i had one of the 3 go bad and i had to switch them out.
should i use the accesory hookup for the headlight? also the po had a 15 watt fuse for the headlight and i switched it out for the 10 watt. i also replaced the headlight relay just in case.
the headlight used to dim a bit at idle when i applied the brakes but now it's the opposite...??? hmmm
i am currently searching as well but i haven't seen a similar problem yet.

the bike still runs just fine besides the light, no missing or stumbling and the battery is good. i am currently using one of the expensive maintenance free batteries. with the meter is shows 12.8 voltz.
this is a 79 standard so it doesn't have a seperate main fuse outside the fuse box. and i have the wiring diagram and it all looks correct. i will go check all the connections one more time. also i have used the electric cleaner on all the connectors while i have been checking this.
thanks!!!

[DiverRay]

Check ALL the ground connections! The big one being the rear bolt on the Reg/Rec. That is the one ALL the harness grounds terminate. I use a product called "No-Ox", but Randy I think said that anti seize will work as well. They are both CONDUCTIVE, and protects the ground points.

[tw1980]

Yes redo the ground connections.Make sure they all have a star washer and are treated with something to inhibit rust and oxidation(grease,oil,anti seize,dialectic grease etc... Next have you treated all your electrical plugs with dielectric grease?My guess is you have a bad connection.

[yamahansolo]

i cleaned and coated them yesterday.

if the main ground was no good then i would think the bike would run like poo...???

after installing headers on my 92 camaro a few years ago i forgot to reattatch the ground wire that was on the back of one of the cylinders heads and the car ran like crap until i figured out i left off the ground

[oldyam80sg]

You said the PO did a fuse block mod and it is almost like stock.I would replace the fuse block with one of TC's fuse blocks as the blade fuses are the way to go.Besides the glass fuses are getting scarce and the blade fuses are available more places.

[yamahansolo]

before i replace it i want to fix the problem. i have plenty of the fuses here, they have them at autozone and advanced. the fuse box he replaced it with have the longer glass fuses. i only say 1 pack of the short ones at az.

my question is what would cause the headlight to increase in brightness while holding the brake lever. even at idle this is the opposite of how it normally runs.
thanks

[yamahansolo]

ok i pulled the tank and the ground wires on the reg/rect were a little loose. i scrubbed them down got them nice and shiny and then used the electrical cleaner on them and after i got it all back together it still is dim, the headlight looks like a flashlight bulb going dead. until you hit the brakes and then it lights up super bright. i also redid the battery ground again and this was no help.

any more ideas?
thanks

[DiverRay]

The brake light is probably adding a second path to ground. If you can make a "temp" ground wire from about 3' of 14 gauge wire and two alligator clamps, try this experiment. With the bike running, connect the clamp to the negitive battery post, and the other end to a ground connection inside the headlight bucket. If the light get brighter, you have a ground issue. If not, you have a connection issue on the positive side of the circuit.

[yamahansolo]

thanks!
i'll try that tommorow, i have to sleep soon.
i was wondering if it was something like that. but the dashlights dim as well and i know they are also connected to the relay so could the ground issue be around the headlight relay and maybe not in the bucket? or would this issue move from the bucket through the relay?

[DiverRay]

IIRC, the grounds in the headlight area all run back to the grounds under the tank. Also, if the ground strap from the battery to the frame, and then the frame to engine is not CLEAN, you can have problems. The relay ground just runs the relay. A second ground wire from inside the bucket to the frame may be all you need for now!

[yamahansolo]

recleaned all the ground straps. and i ran another ground for the headlight... still no joy
it was rather dark riding home tonight.

that hadlight has only been in there about 2 months. i was using one of those silverstars but it didn't give a good beam pattern with my lens. i accdentally bought a 9003 and my lens says h4 and after holding the two next to each other there is a slight difference in where the filiments are. this was giving me a funky triangular pattern and it was hard to see at night.

any more ideas?

[yamahansolo]

ok next update.

i bypassed the rlu and it still is very very dim... i also tried hooking the wire for the light up to a different spot in the fuse box to see if the brown wire was bad but it still was very very dim. but running it to the other connector in the bucket it is super bright! but i can't switch to high because i was bypassing the whole headlight path.

i replaced the relay also. i have no idea where the diode is but would the diode fail completly or could it just be shorting a little?
also i took apart the handlebar switch box again and recleaned it but still nothing. so the problem has to be after the fuse box but before the headlight
thanks

[DiverRay]

The best thing to do is trace the wires from the fuse. Every time you come to a connector of ANY TYPE, clean and dielectric grease it. Be sure to check for a tight fit on both the flat and bullet connectors. You can squeeze the connectors just a little to make them a little more snug.

[XSPastor]

Hmmm

i accdentally bought a 9003

Is it possible that the wrong bulb could be part of the problem?

JAT

[yamahansolo]

i took the bulb out 2 months ago and it has the h4 and it worked up until 1 day last week.