1 K75 Electrical Gremlin Sat Nov 28, 2020 11:42 pm
jjefferies
Life time member
Was winterizing both my K75's today ('90 and '91). Adding sea foam and running them to get it through out their fuel systems. Had both bikes running on their center stands. Shut them down. Took Silver out around the block. Came back intending to do the same with Red only Red wouldn't start. Soon as I turned the key on the lights would blink once and then nada. Even the clock went and reset. A guru friend suggested it might be the battery which is fairly old. So I took it out and attached a battery tender. It came right back and went to 14.3 volts. Tried a heater wire across the terminals to stress test it. It got the wire hot but stayed above 12 volts and came right back with the battery tender. Checked resistance from battery lead to ground. Less than 1 ohm. Put a good quality VOM on the battery terminals. Got a reading in the megohms - well there has to be some power bled off to the clock. But when I turned the switch to the 1st position (the parking lights) the resistnace dropped to 1.2 ohms. When I turned the switch all the way to running, the resistnace jumped up to 8.8 ohms. All the fuses appear to be good, i.e. can't see any burned out pieces.
Any thoughts or suggestions as where to start? Only recent work on the bike was to add a "BMW motometer" voltmeter to the system.I will start by removing it from the circuitry. Just a debugging problem. Next would be to look into the dreaded starter motor short circuit. Though the fact that the voltage drop starts when the parking lights are turned on would argue for other issues.
Thanks for any thoughtful suggestions.
J.
Any thoughts or suggestions as where to start? Only recent work on the bike was to add a "BMW motometer" voltmeter to the system.I will start by removing it from the circuitry. Just a debugging problem. Next would be to look into the dreaded starter motor short circuit. Though the fact that the voltage drop starts when the parking lights are turned on would argue for other issues.
Thanks for any thoughtful suggestions.
J.