Just another charging thread...

[dpotter58]

I started having a problem with my headlight not coming on while running. During the “troubleshooting” I found that if I wiggled the wires under the tank it would come on. In pulling the wires apart, I found the wire for the diode wire was broke so I pulled the diode out, plugged it together, put some heat shrink on it and went about my business.
Soon after, I had a dead battery and since it had been fine prior to the headlight issue, I checked the charging and was only getting ~11.8 volts even at higher rpm.
My tach works, wires for the stator checked good so I kept looking for a problem.
What I found was the omron relay 3H5-00 was very hot. As soon as I unplugged it the voltage went up to a little over 12 and when I sped the engine up, the voltage went to about 13.5 or so.
I bought some deoxit and cleaned up a bunch of the connectors in the headlight and charging circuit but when I plug the relay in it heats up and voltage drops. I had another relay from a charging bike and and plugged it in but found the same problem.
So, is this a problem of not having the diode and if so what size do I need to get? If not, what else could it be?

[bikerphil]

Might want to check the alternator connector behind the fuse panel, they corrode and sometimes melt. If you unplug the headlight relay and jump red/yel and blu/blk, the headlight will come on with the key.

[dpotter58]

Might want to check the alternator connector behind the fuse panel, they corrode and sometimes melt.

Yep. It was one of the ones I pulled and cleaned. It's good

[Ivan]

That diode is part of the circuit that holds the headlight on after the engine has started, until the switch is turned off.

It may be allowing a draw in the opposite direction. I would suggest taking the old diode into a Radio Shack with the geekiest looking nerd working there and ask him to set you up. Most of the time you want to find a Radio Shack that doesn't sell cell phones. Most any electronics supply shop would have it as well.

Just be sure to install it the right way. They usually have a stripe on them to indicate the positive side, so make sure it goes in the same way as it came out.

[dpotter58]

That diode is part of the circuit that holds the headlight on after the engine has started, until the switch is turned off.

It may be allowing a draw in the opposite direction. I would suggest taking the old diode into a Radio Shack with the geekiest looking nerd working there and ask him to set you up. Most of the time you want to find a Radio Shack that doesn't sell cell phones. Most any electronics supply shop would have it as well.

Just be sure to install it the right way. They usually have a stripe on them to indicate the positive side, so make sure it goes in the same way as it came out.

If I hadn't been a dumb azz and tossed it I would. I found a thread with the correct size. I'll pick some up tomorrow

[randy]

Dwayne any diode above 1amp will do. Install it with the striped end toward the relay. Last time I was at the shack for diodes they had a pack of two 6amp for a couple of bucks.

[dpotter58]

Dwayne any diode above 1amp will do. Install it with the striped end toward the relay. Last time I was at the shack for diodes they had a pack of two 6amp for a couple of bucks.

Do you think the lack of the diode is the problem?

[3Phase]

Do you think the lack of the diode is the problem?

Could be. The White wire with the diode supplies pulsed 12V DC to the headlight relay to turn it on when the engine starts and the charging system begins working. Once the relay is on there is a second diode inside the headlight relay that keeps the relay coil energized from the RLU side of the relay.

When the headlight relay is 'latched' on, the diode on the White wire now isolates the Regulator/Rectifier and the stator from the DC voltage being supplied to the relay coil by the internal diode. There should never be any DC in any of the White wires from the stator.

If the diode on the White wire is shorted or replaced with a jumper the headlight relay will feed 12V DC back through the stator and the Regulator/Rectifier.

Don't do that.


Regards,

Scott

[petejw]

hey dpotter58,
ive had this problem for ages and have never found a fix,
the light would work ok for a while then not work at all, most of the time wiggling the wires on the left side of the tank would fix it, last time tho
it went out 4 ages and i had to tape the 'pass' switch down
to have a light, its still does it occassionally,
if you find the problem
id sure like to hear about it.

[skids]

It is just one more good reason to trash the locking relay system and install an automotive switchable relay in its place.

[dpotter58]

Putting in a new diode did the trick. Thanks for the info... You folks on channel 11 are the best. Well, some of ya are

[cywelchjr]

It is just one more good reason to trash the locking relay system and install an automotive switchable relay in its place.

The locking relay works just fine as long as everything is working properly. A common failure is the diode in the harness under the tank. Replace that with a nice new one and if the charging system is working things will be fine. It's one of your first signs that the charging system is not working, that the headlight doesn't come on.

[petejw]

can someone tell me where abouts this diode is situated,
is it wrapped up in the wirering loom?

tia

[dpotter58]

under the gastank look in front of the regulator in the harness you will see a white wire under the tape, mine was looped in the bundle near the reserve lighting device. The diaode is in a clear plastic protector kind a thing...

[petejw]

thanks for that.