Electrically Dead

[rickt]

Still recovering from a cycle accident May a year ago. Got the '78 GS750 out today for the first time this year. Since I completed the restoration ~2 years ago, all electrics worked just as they should. Put in the freshly charged battery today, turned the key and nothing. No lights, horn, starter, etc. Battery is giving 12.7 v at rest. Checked the fuse - 12.7 V on both ends of the fused holder.

This pretty much exhausts my electrical trouble-shooting skills. Hoping I can get some step-by-step advice on how I can identify the problem.

Thanks,
rickt

[Guest]

Wiggle the fuses.
Maybe one is bad but only looks good.

[rickt]

More information

Finally got back to trouble-shooting the electrical problem. Got into the headlight shell and am getting 12.7 v in the red wire running from the positive battery terminal. So, it would appear the wiring is ok from the battery to the headlight shell. When I connect the four-prong plug containing the red wire to the ignition switch plug and the switch is turned "on," I should get 12 v coming from the orange ignition switch wire. When I checked the orange wire (at the horn), I see less than 1 v.

Does this result indicate that the ignition switch is the failure point?

If so, can the switch be replaced keeping the original key code?

Thanks

[Guest]

The switch is under the key tumbler assembly. I believe they do come apart for maintenance.

[rickt]

Simple Solution

I failed to check the obvious. Although the resting battery showed 12.7v on the voltmeter and the same voltage was observed in the headlight shell, the battery was essentially "dead." It provided a constant green light on the battery tender, but when placed under load, it was hopelessly dead. Simply replacing with a different battery produced a quick reliable start!