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'77 R75/7 No electrical power

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John Ehrhart
(@rider17)
Posts: 43
Trusted Member
Topic starter
 

After disassembling the turn signal switch, I found the entire assembly in poor condition from a previous repair attempt. I found another /7 switch, installed, and all works now.

Next, a new left handlebar switch: I have no headlight, though it will flash.

Thanks for all the help.

 
Posted : 07/30/2022 06:04
Richard W
(@wobbly)
Posts: 2597
Member
 

Logical Assumptions

► We will start with the assumption that since the Passing Switch works, that both the bulb and fuse are good. This has about an 80% chance of being a good assumption. However, the Passing Switch may take power from somewhere else. (The fuse in question is the fuse between Gray and Gray/Black on the multi-color board.)

► We will also start with the assumption that you have also dipped both ends of BOTH fuses into the No-Ox-Id electrical connection anti-oxidation compound as you were previously instructed.

► Some year models require the Ignition Switch moved to a second position, because the bike pre-dates the DOT mandated "motorcycle headlamps ON 24/7" federal law. We assume the Ignition Switch is in the correct position for Head Lamp operation as indicated (hopefully) by the Tail Lamp turning ON.

 

Test Procedure

• Again, use the Mechanic's Test Lamp to test for the presence of power going into the switch on the Gray/Blk (or possibly Gray) wire. Then test for power coming out on Yellow (Lo beam) and White (Hi beam). Power going in, nothing coming out = Bad handle bar switch. Simple and straightforward.

Most proabably the same fool that "fixed" the LH switch pack has also been into the RH switch pack.

• In extenuating cases the Gray wire may not be receiving power from its source, the Ignition Switch. In this case testing for electrical power on both sides of the Gray & Gray/Blk fuse (when the Ignition Switch is in the correct position) will tell the story. But if that was faulty, then the Tail Lamp would also not be working and you have given NO hints as to the operation of the Tail Lamp.

 

Hope this helps.

This post was modified 2 years ago 2 times by Richard W

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 07/31/2022 06:28
John Ehrhart
(@rider17)
Posts: 43
Trusted Member
Topic starter
 

I've acquired a new assembly. Alas, it lacks the headlight switch, I surmise from a year with headlights always on.

Can I use it anyway, and do I need a load shunt for starting?

 
Posted : 08/02/2022 04:58
Richard W
(@wobbly)
Posts: 2597
Member
 

► Sorry, can't help you with connection of non-standard switch products via long distance.

► Still no information forthcoming on the operation of the tail lamp, which is essential (foundational) to the entire question and logic of light operation diagnostics.

This post was modified 2 years ago 2 times by Richard W

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 08/02/2022 15:55
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