Author Topic: Re: K100LT Electrical / Ignition Switch Issue  (Read 9520 times)

Offline Konorway99

  • Curious
  • Posts: 4
Re: K100LT Electrical / Ignition Switch Issue
« on: June 07, 2025, 11:27:30 AM »
Hello,

What should I do to figure out what isn’t working?

I was riding at 45mph, all of a sudden no power, no electrics. Turning the key only shuts off the clock. No lights turn on.

Turns out the battery had the metal bar that holds it down touching both terminals on the battery. That battery is now dead and replaced with a new one.

With a new battery try the starter relay shows 12.85 volts even when the bike is off.

I have just cleaned the ignition switch and tested for continuity like in the guide. I have continuity for many more wires than listed at all positions. Even off. Does this tell me that something else is the issue or do I need a new ignition switch.

After cleaning the clock stays on when turning the key.

What do I check?
Is it a ground issue?
Ignition switch? Starter relay?

This is my first K-bike and first post so I am definitely needing some help.
  • Fayetteville, AR
  • 1996 BMW K1100LT
1996 BMW K1100LT
1990 BMW K100LT - Sold

Offline frankenduck

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  • Posts: 5511
Re: K100LT Electrical / Ignition Switch Issue
« Reply #1 on: June 07, 2025, 09:43:04 PM »
The starter relay is wired directly to the battery so it should have the same voltage as the battery regardless of the ignition key position.
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Offline Laitch

  • Faster than a speeding pullet
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Re: K100LT Electrical / Ignition Switch Issue
« Reply #2 on: June 08, 2025, 08:18:57 AM »
I have just cleaned the ignition switch and tested for continuity like in the guide. I have continuity for many more wires than listed at all positions.
After cleaning the clock stays on when turning the key.
A continuity test only shows that there is a path for electricity to flow if the wire is energized.The clock is always running regardless of key position.Check for blown fuses.Check the plug that attaches to the fuel injection control unit under the seat. Verify that it is latched securely and cannot be unplug by pulling outward from its right end where the cord is attached.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Konorway99

  • Curious
  • Posts: 4
Re: K100LT Electrical / Ignition Switch Issue
« Reply #3 on: June 08, 2025, 07:38:29 PM »
Hello, thanks for your advice.

I checked all the fuses and all are good.

Fuses 1,2,6,7 read the same voltage as the battery. Fuses 3,4,5 read 0.

The connector for the fuel control unit is latched in, even still has factory zip ties.

I should have included more detail. Initially turning the key to on turned off the clock. Now after cleaning the ignition it is always on. Additionally the continuity test I did on the ignition is the one from the ignition cleaning guide . It has a table that specifies where you should see continuity if I am reading it right. I get spark between some wires even in the off position.

More information as I don’t know what is helpful: when testing for continuity from the ground on the battery to the ignition all wires have continuity except for the red. When testing from the positive terminal all 4 wires have continuity.

Is there any way to know if it is a bad ground, and which ground in that case to check?
  • Fayetteville, AR
  • 1996 BMW K1100LT
1996 BMW K1100LT
1990 BMW K100LT - Sold

Tags: electrical ignition