Please Help! Relay Issue

[FormerGlory]

This is a follow-on to my asking for help with the left control wiring. I think I'm ok there now...but still have no power to my lighting (headlight, turn signals, gauge lighting, etc).

I pulled out the shop manual schematics and traced the lighting power back to outputs coming from the Reserve Lighting Unit (RLU). The RLU is powered by 12V input coming from a relay which is shown in the picture link below. The 12V power to power this relay comes directly from the R/Y wire (output from the fuse box) and goes directly to this relay when you turn the key. With the Key in the ON position, I have 12V at the back of the relay connector (R/Y wire) which plugs directly into this relay. The relay should be providing 12V output on the L/B wire to power the Reserve Lighting Unit...but their is no 12V output on this wire. Bad relay, right? No relay power out, no power to the Reserve Lighting, and therefore no power to the headlight, etc.

Anyone know what this relay is, and where I get a replacement? Its just called a "Relay" on the schematics. Picture links below.

http://picturepush.com/public/7865638
http://picturepush.com/public/7865643

Thanks!

[FormerGlory]

I tracked it down to a Yamaha Part #3H58195000 RELAY ASSY. Local dealer wants $99.99 for it. It's just a friggin' relay!

Anyone have one laying around, or know of an aftermarket direct replacement?

Thanks

[mack]

I'm not experienced

enough to provide assistance in this regard ( I know what I would do ) but if 3 phase or Gezzer come on line later, pay attention to what they say.

[bikerphil]

You do know that the bike must be running for the headlight to come on? It is triggered by voltage given off by the alternator.

That being said, regarding the relay:
Either take it apart and fix it, it's usually a broken solder joint or unplug it and bypass it by jumping the blu/blk and red/yel in the harness connector.

If you have an 80-81 model, there is a diode in the harness just below the relay that goes bad preventing the relay from triggering when the bike starts.

[FormerGlory]

Mine is the '80 SG, and according to my schematics I don't have a diode on the 12V line between the fuse's 12V output and the relay. I have the necessary 12V on the R/Y wire at the back of the connector that plugs into the relay so power is making it to the relay. If the relay was triggering...I should have a constant 12V out on the L/B wire that exits the relay and feeds the Reserve Lighting Unit. No 12V on the L/B wire. Gotta be the relay. Checked the input ground wire (B). It's good.

[bikerphil]

Mine is the '80 SG, and according to my schematics I don't have a diode on the 12V line between the fuse's 12V output and the relay.

The diode is in the white trigger wire down a bit from the relay. Does your headlight work if you temporarily bypass the relay?

[crazy steve]

To clarify what Phil said a bit, the power for the relay is coming in on the white wire through the diode. The 12V from the fuse panel is to power the lights, not the relay....

[FormerGlory]

I hadn't thought about the white wire. If its the trigger, does the engine have to be running to get a signal from the rectifier on the white wire? If so, that's the problem. I can't start the engine just yet until I hook up fuel lines, tank, and add engine oil, etc.

I suspect the engine has to be running since with the key ON, there's no voltage on the white wire.

[crazy steve]

Yes, until the motor starts and the stator puts out voltage, the relay won't operate. If you want to check operation of the lights without the motor running, jumper between the red/yellow and blue/black wires.

[FormerGlory]

Thanks. I jumped the wires and the headlight works fine. I have to assume the rectifier, diode and white wire are good. Appreciate the insight.

Now, why do my carbs flood when the petcocks are on reserve (engine off)? I've changed nothing, except remove the carbs and reinstall them.

Thanks

[jetmechmarty]

flooding carbs.

Now, why do my carbs flood when the petcocks are on reserve (engine off)? I've changed nothing, except remove the carbs and reinstall them.

Thanks

We should probably start another thread. Is your fuel system stock? If so, your vacuum shutoff valve (octopus) is not functioning, and whichever carbs are leaking have faulty float valves. (needles & seats) You should also be experiencing the same situation with the petcocks selected to "ON" and in "PRIME". If your set-up is stock, you will bypass the vacuum shutoff with "PRIME" selected.

[FormerGlory]

Starting another one...