Needed - electrical guru

[Keithh]

Greeting all.

Yes. I'm still trying to track down way I do not get a spark. I cleaned all the connections, it gets voltage where it should, handlebar switch has been cleaned (again), etc. I'm pretty sure that at this point the igition circuits are oaky, but I started wondering about possible grounds. Leads to a question:

When I unplug the brown wires from the fuse box (thanks TC) and do a general continuity check I found that brown wires feeding the fuse box (all three brown wires) show a complete path to ground (one meter probe to frame, other to brown wires). It is the same with key on or off. I kinda throught this was odd, but I admit that I'm still on the learning curve for all aspects on this electrical system. From what I see, the brown wires go to the key switch, with only taps to the regulator and alternator. When I disconnect the plug with brown wire to the regulator, the continuity stops and only comes on when the key is turned to the on position. When I removed the wire to the alternator with the regulator plugged back in, the ground returns, so I'm pretty sure the regulator is the source. Now, is this normal??? I also noticed that the headlight comes on even when you are just trying to kick start the bike - not even running - just one kick. Again, seems odd as the alternator couldn't be putting out much of anything at the point to close the relay.

Okay - I'm already a bit wordy, but I wanted to share all that I know in the hopes one of you smart folks may have any thoughts.

Thanks!

Keith

[crazy steve]

You need to check your regulator.... There's a procedure in the manual using a ohmmeter, you probably have either a bad diode or the IC 'regulator' part is bad.

[GLoweVA]

Keith, after stopping at TC's this afternoon, I did swing by your place, but it looked like nobody was home.
TC has a spare TCI that he lent me to let you try, but like I said, you weren't home.
If you want, I can swing by just about anytime during the weekend and even after work during the week (except Mon & Wed)
I think if we put our heads together we can get thru these electrical gremlins of yours.

When I unplug the brown wires from the fuse box (thanks TC) and do a general continuity check I found that brown wires feeding the fuse box (all three brown wires) show a complete path to ground (one meter probe to frame, other to brown wires). It is the same with key on or off.

All 3 brown wires from the fuse block are connected together so they should all read the same, Looking at the wiring diagram it looks like it goes thru the field coil then to the rectifier then to ground, so I can see that it would likely read continuity.

As far as the kickstarter and headlight, that makes sense to me if the motor is spining fast enough so the alternator puts out enough to pick up the headlight relay.

[GLoweVA]

Update

So here's some more info on what's going on with Keith's bike:

Now, just to add to confusion, the Yamaha decided to start. Note that I didn't say I fixed it - it was truly a decision on its part. But maybe we are getting closer - I noted that the instument lights and head light didn't come on. The bike started several times on the button without a problem. I need to do some digging - prehaps there is something related to that. I'll be opening up the headlight in the next day or so to see if anything is out a whack in there.

If I can just get my photobucket to work on my phone, I'd upload a schematic of the lighting circuit for him.

[GLoweVA]

diagram

Let's try this:


Here's the advice that I gave him via PM today:

If I read the wiring diagram right, the headlight and dash lights won't come on if the headllight relay doesn't pick up. (also with the '78 I think there's an on/off switch on the bars for the lights) The 80 and newer ones, the headlight relay is a 6V relay (due to the diode in the circuit from the alternator) in the 78-79's this should be a 12V relay.
In other words, the yellow wire into the headlight relay should see a full sine wave while the engine is running.
Maybe if you've got the wrong relay in there, it could drain the system in some wierd way and thus be the cause of your intermitent starts. (and maybe explain why your lights came on with the kickstarter)

I'd say try pulling the plug on that relay (under the tank up very close to the neck/bars)(If you remember my bike you saw my jumper for my headlight relay.)
The only thing it runs is the headlight and dash lights. If you can start the bike every time after pulling that plug, then that might be it.

Now can any of you 78/79 owners get a resistance reading on your headlight relay (yellow to black) to check the relay's coil to see if it's any different than the 80/81's relay.
80 part number: 3H5-81950-00-00
79 part number: 2H7-81950-10-00

[crazy steve]

....All 3 brown wires from the fuse block are connected together so they should all read the same, Looking at the wiring diagram it looks like it goes thru the field coil then to the rectifier then to ground, so I can see that it would likely read continuity.

As far as the kickstarter and headlight, that makes sense to me if the motor is spinning fast enough so the alternator puts out enough to pick up the headlight relay.

Nope, you shouldn't have a ground path there. The regulator/rectifier has diodes that are supposed to prevent a direct path for 12V+ power to ground. If you have a failed diode, then that's possible; that's why I suggest checking the regulator. Otherwise, look for a damaged wire going to ground, although if unplugging the regulator clears it that's not likely.

When checking for continuity and/or resistance, are you pulling the fuses? If not, you'll get readings to ground through other parts of the circuits. The key to troubleshooting electrical is to isolate various parts of a circuit, clearing each piece before moving on. Failure to do this will have you chasing your tail...

Look here: http://www.xs11.com/forum/showthread.php?t=35337 .... for a overview of the wiring.

As to the headlight relay, I don't think that's the problem. There is no direct connection between the relay coil and the brown wire. If you are having starting problems, unplugging it will reduce load when starting to help with the troubleshooting process. Get the bike running and check the charging system for proper operation first, then if plugging the relay in causes a problem you'll immediately know it.

[GLoweVA]

His problem is not so much the cranking as it's an intermintent sparking (or no sparking) while trying to start.
Some times he'll get spark and it'll start/run, other times, no spark, so it won't run.

[crazy steve]

Has the fuse panel been replaced?

[ManagerMike]

Just a thought starter... (seems you are talking about a 78?) intermittent no spark and headlamp coming on when it shouldn't sounds like it may be related to the RH handlebar switch assembly in the form of pinched wiring or something similar, it does house both the kill switch and the headlamp switch. As far as the headlamp relay goes, I replaced mine some time ago with a standard Bosch type automotive one, so the coil resistance can be disregarded as a possible culprit of your symptoms.
Good luck, Mike.

[GLoweVA]

Steve, he put a new TC block on and also got another wiring harness a few weeks ago too.

Mike, I think his is a 79, but could be a 78. I think the only real difference would be the headlight on/off switch.
I do like the idea of looking for a wiring issue near the kill switch though. (because that part of the wiring wouldn't have gotten swapped out during the harness swap that he did)

As far as the headlight relay, the older ones are a 12V ones, but a 12V one won't work on the 80/81s because of the diode. (That's why I've got mine jumpered out) That's why I'm wondering if the PO might have put an 80/81 relay in and that might be an issue.

Note: this is Keith's bike, not mine. I'm just trying to help him figure it out and he doesn't get online that often.

[crazy steve]

...As far as the headlight relay, the older ones are a 12V ones, but a 12V one won't work on the 80/81s because of the diode. (That's why I've got mine jumpered out) That's why I'm wondering if the PO might have put an 80/81 relay in and that might be an issue..

The early/late relays don't directly interchange because of different plugs. But they both function exactly the same, it's the wiring harness wiring that's different.

I'm assuming the swapped harness was a '78-79 piece; if it wasn't, you may have issues with the differences between the two types.

[mikubuilder]

headlight relay

on mine 79' standard headlight comes on after few kicks, so I believe it's all you need to power up headlight relay and make the headlight "stay"on...

[Brad]

Let's try this:


Here's the advice that I gave him via PM today:



Now can any of you 78/79 owners get a resistance reading on your headlight relay (yellow to black) to check the relay's coil to see if it's any different than the 80/81's relay.
80 part number: 3H5-81950-00-00
79 part number: 2H7-81950-10-00

Hi all, I'm looking for an actual picture of "the main switch" in this image. Wanted to take my bike for a spin last night and no headlight or tail lights.

[GLoweVA]

Wanted to take my bike for a spin last night and no headlight or tail lights.

Brad, If you've got no head light and no tail light then your problem is with the main swtich of the fuse supplying power.
"The main switch" is the key switch. It connects the brown to the blue and the red.
The red coming in should have 12V from the battery via the main fuse
The blue goes out the the tail lights/running lights
The brown goes out and back to the fuse block to the other 3 fuses including the headlight fuse which comes out of the fuse as the red/yellow wire.

Are you having any other symptons other than no lights?
In other words, does it still start? If so then the red to brown makes a connection.
Do you have a test meter? can you check for voltage at your fuse block with the key on/off?

Another possibility is that you may have more than one issue. ie. 2 faults.

[Brad]

Bike starts, key function works proper. I wiggled the main harness leading from the fuse panel just passed the fuel tank bolt and the start button would not work, wiggled it again and the start button worked. I'm going to check my connections, clean them with contact cleaner. See if any solider connections have broken loose due to the fantastic conditions of our roads out here. I did ride down a rough road prior to getting home yesterday. Hope there's not a break in my harness. battery is fine, just put it in a month ago. I do have my battery charger at my house but my meter is at the shop. I only have a test light at my house right now.