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PIAA H4 high low not working but Passing is?

B

bigdog1001

Just got it firing!
Joined
Dec 2, 2012
Messages
17
Location
New Canaan
Figured this was an easy project to upgrade the bulb.....it was but despite troubleshooting the high-low button is doing nothing......the H4 bulb comes on nice and bright when I toggle the passing button so it seems correctly connected. I checked the 15a fuses and intact. Stumped in CT!
 
I think you may have used a wrong bulb. The Breva is supposed to have an H7 for low beam and an H9 for high beam. Both bulbs are single filament, the H4 has a dual filament.

Before trying any more troubleshooting, I suggest you install the correct bulbs.
 
kiwi dave said:
I think you may have used a wrong bulb. The Breva is supposed to have an H7 for low beam and an H9 for high beam. Both bulbs are single filament, the H4 has a dual filament.

Before trying any more troubleshooting, I suggest you install the correct bulbs.
Click to expand...


Dave, he posted in the Griso section, so I'm assuming he has a Griso. It uses an H4. Have you followed the troubleshooting procedures outlined here? https://www.guzzitech.com/forums/threads/troubleshooting-circuits.3001/ I hope you have a good voltmeter.
 
OK, I'll have another go. If neither the low or high beam is working, then I'd be suspecting the light relay which supplies power to the high-low beam switch. The high beam flash button gets it's power directly from the ignition switch.

Of course, it might be the wiring between the relay and the high-low switch, or the switch itself. But I would check the relay first.
 
The passing switch typically lights up both filaments. It sounds like your bulb is wired wrong inside. There are two powers, one for high and one for low, and a ground. If the ground is where either the high or the low power is supposed to be you could get the results you report. I assume the old bulb worked, so that means the new bulb is bad. Is it made in China?
 
So I started the bike up and now the high beam comes on and stays on......still nothing on the low beam. Next onto the relay. Thanks for the input.
 
The light relay feeds the high-low beam switch, and therefore should affect both high and low beams. The relay may be faulty and/or intermittent, but methinks it's not your only problem.
 
You can check the relays by playing "musical relays" under the seat. I switched out the high beam and low beam relays on my 07 Griso and everything worked again. I wouldn't touch the fuel injection relay which is part of the array under the seat. I did buy a new relay which I keep under the seat - just in case. All the relays in that row are the same.

I really wasn't that concerned with the high beam, I don't use it that much. I was told the low beam relay on my 07 Griso is part of the charging circuit. No low beam -- no charging.

After rotating the relays, I haven't had a problem for 4 months or so.

I chalk it up to Italian electrics. I've had a fair amount of experience with Aflas, Fiats and their electrical gremlins.
 
kiwi dave said:
Now, I'm really confused. I can't find the high beam and low beam relays on the wiring diagram, neither for the 2V nor the 8V versions of the Griso. Are we talking about the same model?
Click to expand...

After looking at the wiring diagram I downloaded from Guzzitech I think you're right! I must have switched the starter relay with the headlight relay. I can't remember where I got the information that the the first two relays were both lights. Either way it worked for me which really makes the fix screwy. maybe it was just a connection problem but I bought a spare - just in case.

Pull up the seat and look at the right side next to the airbox you should see a row of relays beside the airbox. You might have to take off the "seat shroud" bodywork. Sorry, I can't remember.

Page 42 (electrical system 2) of the Griso 1100 parts manual shows the relays. I switched the first two relays (the ones closest to the headset). The next relays are the fuel injection but check the wire colors just to be sure. In my case I usually check the wire colors three times and even trace the wires because I'm afraid of screwing it up.
 
Well in terms of troubleshooting I just tried disconnecting the battery for 5 minutes and then reconnecting and starting her up. Success! Now the low-high beam switch is working and so is the light bulb! My relays and main fuses were all intact so I figured I would try the battery. I pulled the negative connection off, waited 5 mins and reconnected and started it. Good luck.
 
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