Electrical problems and updates

[Keithh]

Thanks for all the insights - I'll be ripping into everything, especially ones I haven't touched yet. I am suspecting the ignition switch may need a cleaning, as the voltage at battery is one value, and checking it at the brown wires at the fuse block with connecters pulled - so it should be just voltage from the ignition switch - but is it at least a half volt or more down just to that point. Tomorrow looks to be busy!

[CaptonZap]

Hey Terry,

I have to disagree with this statement. I experienced this phenomenon myself with an aged battery. IT was able to crank the engine over, but did not have enough reserve capacity to provide the 10.5 volts to the TCI to get it to start. I put the jumper/booster battery JUST on the Ignition fuse circuit and the bike then started just fine with the otherwise weak battery. I replaced the faulty battery and have been able to start it just fine ever since.

T.C.

Another check is to turn the ignition on, jumper the two big terminals on the solenoid, and measure voltage to the TCI while the starter cranks. Use a HEAVY jumper wire, at least as heavy as the wire to the starter. (Or the handle ends of a crusty pair of pliers.)
This is one of those situations that an analog meter provides more useful information than does a digital meter. CZ

[Keithh]

Electrical update

Yup - me again, with the possessed 79 Standard. I removed and cleaned the ignition switch - didn't look bad, but a good cleaning never hurt! I did a little testing at the point. The main red wire to the switch is carrying full battery voltaqge - no loss. Using a set of jumpers so I could work individual circuits at a time reveale that with just the red and brown connected, there was full voltage at the fuse bx - no loss. Add in the blue wire (running lights) and you get a .5 to .7 volt drop at the fuse. Given that the running lights and tail light are on, is that a reasonable voltage drop, or is something wrong in that circuit?

Any thoughts?

Thanks!

Keith

[crazy steve]

Your tail/running lights should draw about 2.7 amps for all four, so yes, that seems a bit excessive. You might have a battery that's getting a bit marginal, but I'd check the lights first. Try pulling all the bulbs, then install them one at a time checking voltage with each one. If you get a bigger drop with one particular lamp, check that one carefully. You may have a low-grade short somewhere...