Evasive /7 Generator Light Problem

[ME 109]

All the connections and wires look good there. Is there some way I could chase it down with a test light?

Not sure where to start with a test light in the pod. More an eyeballing exercise I think, looking at the circuit board for anything astray. Moving the wiring harness at the back of the pod when the light is on may show if there is an issue.

[melville]

I have been having a similar problem with my r100r. I get intermittent light also. When the voltage is low, signal lights will self cancel. I have a glass matt sealed battery. I think it could have to do with the battery in my case. An internal short may be causing drop in voltage. It is very random.

Yes, I had something similar happen when my battery had an intermittent internal break (discontinuity). The gen light came on randomly and eventually it quit taking or holding any charge. I replaced the battery and things have been fine for several years since.

[Seth]

I had similar problems with my Mystic.
The problem was poor connections on the wires to the diode board.
I know you've already checked the connections and changed the diode board.
Just saying.

[Wobbly]

In both cases, fitting a handlebar mounted voltmeter (which used to be an official accessory I believe) would tell you what was going on when the lamp was misbehaving like that.

In my mind, if the lamp is being illuminated, then its circuit is working as planned and is "good". Therefore I don't feel that taking apart the instrument cluster can help you. In fact the circuit board within the cluster is so delicate that disassembly can only hurt it. And a new one is in the hundreds of US dollars.

It's much more likely that the issue is within the voltage regulator, rectifier board, or the BLUE wire that runs between them. Such an issue might be the 4 rubber shock mounts that secure the rectifier board being broken (a common occurrence), but I'm guessing.

[Seth]

If memory serves me, it was the ground wire that was causing me my most problems. The heat shielding on the terminal end was melted. I made a new wire and switched to solid mounts. No more problems.

[Wobbly]

If you have the solid mounts then you may not need the short ground wire. That was needed becasue the original rubber mounting blocks for the rectifier board acted as electrical insulators, and kept the rectifier from making connection to the Return (what you call Ground).

[BillB]

I am waiting on parts at the moment but will be sure to give the wiring harness in the back of the headlight a shake when I get it going again. By eye, everything looks tight and clean there. In the schematics, I see possible ground wires but not how they are hooked up. Have people tried different things?

[Wobbly]

Are you still using the OEM voltage regulator in the tin can ? Those are mechanical regulators with coils, springs, and contacts which can give up and/or come out of adjustment. They go bad all the time. There were several companies that introduced all-electronic regulators that are form, fit, and function identical to the Bosch unit, except they have NO moving parts.

Seriously suggest you go to Ebay and look up one of these units for $20 delivered and install it. Ebay item 272655228783.

[BillB]

I have been using one of the OEM regulators for some time and been quite happy with it, but after trying a couple more variations with the other new parts and coming back to the same problem, I decided to try the old diode board again, mostly on the let's go back to the basics theory. With a 25 mile test ride, it worked fine. Now the question is can I get at least another 225 miles to break the 100,000 mark with the bike. . .

[Gibson]

I know its an old thread, but Seth, for my bike you nailed it. I replaced the battery a week ago so I measured the charge voltage. Not charging at all! I was working on the bike this weekend (rain in Northeast). One of my rubber diode board mounts was broken. Also the ground wires looked overheated. I went with solid aluminum mounts. Board bench tested fine. I think my nest project will be to move the diode board back by the battery. There is lots of room on top of the battery for it.