Yes, those seem like the likeliest possiblities at this point. I assume that contacts T1 and T1 prime on the PCB relate to the 7L circuit, since those are the ones with no connections present on the blue flexi overlay , and we've concluded that I have an '86 or later overlay; and contacts T2 and T2 prime are for the 4L circuit.
Since I can't really troubleshoot the PCB or overlay, except for looking for broken connections, I guess (other than living with it) my best option is to look for used parts that aren't too expensive to take a chance on.
I did come across this modification that was posted in 2002, but it seems like this would be more pertinent to a bad sensor problem than to a problem inside the PCB or blue flexi overlay:
"Early K-bike Fuel Light Fix
By Jim Solberg
September 2002
K-Tech Page Maintainer's Note: This will only work for early K-series bikes. Certainly those with the amber 7l light and the red 4l light, later ones up to the point where the analog sender was installed.
Purchase two 1 K OHM potentiometers from Radio Shack, #271-342, for $1.49 each. Splice one into the brown/white (4 liter) wire and the other one into the brown/black (7 liter) wire, where the wires go into the tank.
Measure 4 liters of fuel into an empty tank. Adjust the potentiometer for the red light so it comes on at the 4 liter content in the tank.
Obviously, the other potentiometer should be set so that the yellow light comes on at the 7 liter level. Of course, you could be creative and set them to come on at any level you desire.
Rather than empty the tank, I emptied almost all of it, then ran the bike until it ran out of gas, so I would have a true indication of liters remaining of useable capacity.
You can get as fancy or simple as you want with the installation. I mounted the pots in a small plastic box, with the adjustment screws accessible through two small holes drilled in the box. I also mounted a small switch through the box and wired it to be able to disconnect everything from the fuel lights just in case the fix didn't work. I spliced in enough wire to be able to mount the box to a frame member just behind the right side cover. I filled the box with silicone, completely covering the pots and switch, as protection from the elements and vibration.
This fix has worked flawlessly for sixteen years."
Or do you think this would be a workaround for my problem?
Another possibility that occurred to me: people have said that the fuel lights won't come on in "test" mode with the ignition switch on but the bike not running, and fuel in the tank. But I'm assuming that the 4L light should come on when the sensor is hanging out of the empty tank with the ignition on, even though the bike obviously is not running.
Don't know if anyone can confirm this on a working bike: when the fuel is low and you turn the ignition on (position 2), does the low fuel lamp come on before you start the bike?
Thanks.
