Pull the fuse before you pull the new coils back off. Do not fit a larger amp rating than the stamp on the fuse that opened. On this 1976 CB500T the coils had just been replaced, the battery had been charged, and the key did nothing. No lights, no signs of life. Swapping the head fuse and the main fuse brought the lights back. The head fuse was left as a part still to replace, so the rating has to be read off the glass, not remembered.
No lights after ignition work
| What you see | Do | Do not | Shop |
|---|---|---|---|
| Key on, every lamp dead, right after coil work | Swap in a fuse of the same amp as the one that opened | A 20 A fuse because it was in the jar | View Key on, every lamp dead, right after coil work (affiliate) |
| Lights back, one plug still dead | DC volts from the coil's black/white wire to ground | Another coil, yet | View Lights back, one plug still dead (affiliate) |
| Black/white to ground reads about 0 V, lights on, kill switch on Run | The feed is open between the switch and the coil | A condenser with a connector the harness does not have | — |
Affiliate Link • Earns Commission
After the lamps are back
Lights on, and the right plug still quiet, is where this bike went next. The points were sparking. The plug wire was not. Measuring between the two black/white coil feeds showed about 0.6 volts. Measuring one of them to ground showed 0 volts, kill switch on Run, dash lights on.
That is not a coil reading. That is no feed. Those black/white wires drop down the right-bar harness toward the carbs, which is where they have to be followed. The meter is the Klein MM325, on DC volts, red lead in the volt jack.
The coils themselves, and the white crust that started this whole sequence, are the coil guide.