The Airheads Beemer Club is a non-profit club reclaiming the 'Legendary Motorcycles of Germany'

Topic-icon 1973 R75/5 Lights on the Dash

  • DMOSER
  • DMOSER's Avatar Topic Author
  • Offline
  • R100 Level
  • R100 Level
More
2 weeks 1 day ago #5935 by DMOSER
1973 R75/5 Lights on the Dash was created by DMOSER
Hey folks,

An issue I have been trying to track down is when my battery is connected (no key in the ignition) the three lights illuminate on my dash (green, amber, red). No sizzling or popping UNLESS I push the key in...when I do that my points wire melts (after condenser).

I have chased multiple wires, cleaned and inspected for corrosion. I’ve added dielectric grease for safe measure. All I have found is that when I disconnect the red wire at my power relay (left side of frame under the tank), the lights do not illuminate and I’m guessing that because I’ve removed all the power to the dash.

Any help you have would be much appreciated!

VR,

David

Please Log in to join the conversation.

More
1 week 6 days ago #5945 by 8166
Replied by 8166 on topic 1973 R75/5 Lights on the Dash
I'm not familiar with /5 electrical systems, but it appears you soon will be. Get a copy of the electrical schematic for your bike and start tracing wires.

New members to the forum require the first post they make to be approved, and I've just done that.

I also moved your post to the Wrenching category, as Airheads Discussion is a non-technical topic area, and you'll have a better chance of getting an answer in Wrenching.

Good luck!

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 25-26, 2020

Please Log in to join the conversation.

More
1 week 5 days ago - 1 week 5 days ago #5947 by 8053
Replied by 8053 on topic 1973 R75/5 Lights on the Dash
On a /5, The starter relay on the left side of the frame under the fuel tank is the electrical "gateway" to the rest of the system. If your bike is not modified at the relay, the red wires are jumped to parallel inside the relay. One of the red wires will lead to the battery, the other will lead to the main switch. When you push the key all the way in, your ignition circuit should be energized and the indicator lights on the face of the speedo should be illuminated.

If the indicator lights turn on when the battery is connected but the key is "off", there could be an incorrect connection on the circuit board of the main switch.

If I understand your post correctly, your wire from the condenser to the breaker points gets extra hot when you push the key in. (ignition turned on) To my mind this would indicate a direct short at the points. I would test for that by placing a non-conductive object like the corner of a business card between the contacts of the point set, then pull the connector at the condensor and test that wire for continuity to ground using a volt/ohm meter. With the point contacts electrically seperated , the ohm reading should infinite or open. This test should be conducted with the main switch in the off position.

James Strickland, IL. Airmarshal
Last edit: 1 week 5 days ago by 8053.

Please Log in to join the conversation.

Moderators: Wobbly
Time to create page: 1.146 seconds