AAAUGHHHH Electrical quandry

[newmaac]

Ok, electrical Guru's
Last week I started and rode my bike for the first time in months. It started ok, and ran pretty well considering that I didn't even put fresh gas in, just added seafaom and went for a ride.
All electrical and controls worked fine.
Today, I have no headlight, high or low.
Here is what I have tried:

*Opened the headlight bucket, cleaned connections with QD cleaner. Checked for voltage, nothing.

*Checked all fuses, visually and with tester. Power to both sides of all.

*Removed tank and cleaned connectors at the reserve lighting unit.

*Swapped the reserve lighting unit with a spare.

*Removed the left-hand control unit, cleaned contacts @ high/low switch.

*Cussed, swore and banged my hand on the headlight bucket.

There is something simple that I am overlooking but I don't know what it is.

Anybody???

[JWSanders]

You are trying this when the bike is running, right?

If so, check the connections to the headlight relay (under the tank) and make sure its getting AC voltage (directly from the alternator) to the yellow wire on the relay.

If not, start the bike and see if your headlights come on.

[skids]

Isn't the 80 equipped with an inline diode to "straighten out" the AC? I always wondered how a single diode would affect the reading since it is really not AC or consistent DC current.

Originally posted by JWSanders
If so, check the connections to the headlight relay (under the tank) and make sure its getting AC voltage (directly from the alternator) to the yellow wire on the relay.

[DiverRay]

Mike,
If you have a Diode in your '80, it may have fried. You would then have an open on the AC line, and no headlight.
The diode is probably just in line, looks like part of the wire. I would say try to find out the start point of the wire to the relay. If the yellow wire isn't showing any voltage, run another wire from the ignition or from the Alternator pick up point.
I'm gone this weekend, but may have time after work next week to help if you need it.
Ray

[newmaac]

Can you help identify the headlight relay please. I checked a parts microfiche and they were just listed as "relay", not showing which was which.
The one that I thought was for the headlight doesn't have a yellow wire.
A part number or better location description would help.
Thank you

[JWSanders]

I don't have my bike here to check it, but if I remember correctly, it mounts opposite to the tilt switch directly under the center of the tank, just behind the headstock. Between the coils(?) Can't remember for sure...

My diagram shows 4 wires running to it. Red/yellow, blue/black, yellow, and black.

[DiverRay]

Mike,
It should be in front of the tilt switch. Just in front of the cross bar. `according to the wire diagram, the yellow wire goes from the Alt. to the lighting unit.
Ray

[mro]

may, may not help

http://www.yamaha-motor.com/sport/parts/home.aspx

go to your year/model

click electrial 1, item 31 is the only diode listed
should be part# 3h5-81980-00-00

go to electrical 2, item 7 is the only relay listed
should be part# 3h5-81950-00-00

part#'s are only good if same as 80G which I think they are



mro

[newmaac]

Sweet! Thanks guys. This site is awsome!!
The Sharks are kicking A$$, and I am getting good information to get my bike fixed.
I a loving it!!

[newmaac]

OK, I changed the relay, no headlight.
I have not found the diode.
Looking at the wiring diagrahm, it looks like it should be inline in a grey wire.
I have a 4 pin connector at the relay using:
red/yellow, black, white, blue/black.
There is nothing visable (bulge in wire, extra connectors etc...) up near the relay. Is it hidden back behind the plate that holds the fuse panel??
Ray you mentioned bypassing the relay and connecting to another wire at the Alt.
Would it work if I just hooked-up to the assessory power terminal?
If I DO run another wire, what happens to the lighting circuit without a diode in place. Will there be other issues caused by "spiking current" or whatever the diode was supposed to be helping???

Electrical issues are weird to me. If I can't see it, I have a hard time grasping it. I guess if I had a better understanding of the logic that makes it all work......

[John]

If you are going to run another wire to the relay from the acc terminal, then keep in mind that the relay is controlled with AC voltage for the alternator, this is around 7 volts. 12 v DC may not workto latch in the relay. You might as well wire the headlight direct, and bypass the relay. The only problem with that is the headlight will come on with the key, not after the bike starts. You could run the headlight power wire through an oil pressure switch, and that way the light will only come on when there is oil pressure when the engine is running. It would be very easy to do.

[TopCatGr58]

Hey NewMaac,

Okay, replaced the relay, still no light. Have you checked to make sure the bike is charging properly, getting over 14volts at 2500+ rpm?!

Secondly, that WHITE wire is the one from the charging circuit that triggers/latches the relay. I, too, am no electrical guru, remember recently someone stating that the DIODE converts that AC pulses, to DC current, so just bypassing the white wire with a direct tap from the aux. terminal (+) to see if the relay will latch and the headlight come on! IF it does turn on, then the relay is good, and you can run a single pole single throw switch in line from the AUX terminal, or any other Power line you can find, and then to the white wire, so you will have a SWITCHABLE headlight, so it can be OFF when starting, and then flicked on when you throw the switch! You can get handlebar clampable switches, or you can find an automotive one that you could attach to a bolt somewhere on the handlebar area. You could even find a micro switch, and mount it to the control switch set.

But you can also just totally bypass the relay, there's a tech tip about it!
T.C.

[JWSanders]

Originally posted by newmaac
Sweet! Thanks guys. This site is awsome!!
The Sharks are kicking A$$, and I am getting good information to get my bike fixed.
I a loving it!!

Aw, I helped a shark fan. They're gonna take away my fang fingers!! Preds need to wake up!!

[newmaac]

TC, you mentioned a possible low output being my problem.
I checked tonight and found just over 12 volts at idle and 13.8 volts at 2500 RPM.
Not exactly what I was hoping for, but it seems like it should function OK.
Tomorrow I will try the relay replacement, per Sids' tech tip.
http://home.earthlink.net/~sidskids/relay/relay.htm

That seems like a pretty certain way to work around my issue.

Hopefully by this time tomorrow I will post my favorable results.

[Pat Kelly]

Have you checked that the headlight bulb is good ?
Hopw about the ground?