headlights WHY???????

[lost boyz]

2004 yfz450!

i keep having problems with my headlights....

i just went and bought NEW bulbs from the dealership for both right and left headlights....

and a new tail light for ther rear....

i installed them all NEW the worked after install and when i took it riding the other day...i turned them on to check them out and NOTHING!!!!!!!!

now i have no tailight or low beams and the only thing is the left hight beam works....

KEEP in mine that these were all new JUST BOUGHT AND INSTALLED only working for like 10 minutes at the most....

what would make them keep blowing and is the rear bulb and brake light also because i never got to check that out.....

but i want lights because we go out sometimes at night riding...

what could be wrong and whats it take to fix this problem????

thanks!!!!

[RRP]

I'd check the headlight switch first.It sounds like you have a dead short.Did your bulbs blow again? or are they just not working?If they blew,you have a hot wire thats going to ground.Check your harness for bare wires.Try to isolate the problem.Replace just the tail light and see if it blows or keeps working.Process of elimination.Electrical problems are a big pain,but I am sure you wil figure it out.

[lost boyz]

i can use a 1157 for ther rear taillight right???

now does that work as a brake light to or just a light on the rear...????


now all i have is 1 high beam thats all nothing else....

[jshtex]

You need to check your voltage regulator. You need a meter that will test AC voltage, the lights on a yfz run on ac directly off the stator not DC off the battery.

If you test across the connector at the headlights you should see around 12v - 15v AC tops. When I was blowing bulbs mine would go as high as 30+ when the engine was revved up.

FWIW when I replaced my regulator I also had to put in a new stator.

[Puzzled]

I didn't know the YFZ used ac power. That would explain why the machine has to be running in order for the lights to work. What is knocking the voltage down than? The stator puts out X amount of amps to the regulator and the regulator allows the charge to go through to the battery. The regulator is a switch of sorts as it opens and closes as the battery calls for more charge. How is that done to the headlights? OR is it regardless of the amp output from the stator it is still only X amount of volts?!:D

Lostboyz's machine is putting out mad volts to the battery and headlights (30 +/-). That tells me regulator. However if the headlights side step the regulator than that takes it back to the stator.

[jshtex]

It actually regulates the total output on the ac side to the headlights, or at least it is suposed too. My guess would be that yours isn't. The same part also converts the AC to DC and sends that to the battery and ignition (CDI).

[lost boyz]

well i check my headlights

at idle they are 14.5 ( ac voltage )

when i rev up the bike they hit over +35 ( ac voltage )

so what do you think it would be the regulator????

how can i check the stator to make sure its not that???

[Puzzled]

Does your manual have a test procedure?

Like I said to you on the phone I know Harley's. Here is the run down for them.

Don't disconnect or reconnect the stator plug when the bike is running, it can (and will) fry the stator.

To check stator rotor output:
1) disconnect the stator plug
2) start bike
3) set multimeter to VAC
4) read across the stator plug (one probe in each hole)
5) have someone rev the bike up to 2000-3000 RPM
6) stator/rotor output should be 16-20 VAC per 1000 RPM

To check for a shorted or grounded stator:
1) set multimeter to "ohms"
2) read across the stator plug
3) resistance should be 0.2-0.3 ohms
4) now check each stator pin to ground
5) should have no continuity
6) kill engine
7) reconnect stator plug

To check voltage regulator function:
1) set multimeter to VDC
2) check battery voltage...12.5-13.0 VDC
(if the battery isn't fully charged, this test is useless)
3) start bike
4) hold the red lead of the multimeter to the positive post of the battery and the black lead to the negative post.
5) increase engine RPM to at least 2000 RPM
6) multimeter will show regulator charging rate which should be 14.2-14.6 VDC. A brand new fully charged battery will sometimes only indicate 14.0 VDC, anything above 14.6 VDC is cooking the battery (no ****).

[jshtex]

You need to download a service manual and it has directions to ohm the stator out to test it. There are several out there at the various yfz websites.

But if it is hitting 35v when reved up, you definatly need at least the regulator (also called a rectifier).

Do you have any problems with your battery charging, or with your bike banging out in the upper rpm's?

[lost boyz]

no problem with battery starts all the time knock on wood!

no banging in rpm's either!

just popping headlights

[jshtex]

It's possible that you only need the regulator then. The only downside is the possibility that your stator is bad and it took out the regultor. Truthfully I don't even know if that is possible.

I knew my bike had a bad stator way before I found out about the bad regulator. Our bike would cut out at the top of each gear. The dealer said it was the rev limiter but I could tell it wasnt. It didn't stop the bike from winning races so I just overlooked it.

We never ran the lights for XC racing and when we decided to run a night race I bought some high dollar PIAA bulbs to run and blew them up in just a few minutes. Thats why I checked the regulator. Then I figured I might as well replace both....

Good luck with it.