VW latching headlight relay addition...

The hi/lo beam switch on my bike is bad and seems awkward anyway, however the hi beam flash button does work so I decided to wire it to a relay so it controls high and low beam rather than the switch. I wired a common latching headlight relay from a vintage VW (pn 411 941 583b) and it works well....if the headlight switch is off the button still flashes the hi beam, but if the switch is on it toggles between low and high. However since the VW relay wants to see a momentary ground (not battery) to work also had to use an additional standard SPST auto relay so all this might be too much trouble but it does provide a relay for both beams and the headlight switch and relay could be fed directly from the battery by a heavy wire to reduce voltage drop and have brighter lights....also did manage to fit both relays in the headlight shell. Anyway, FWIW here are diagrams of the two relays and some info on how I wired them...also I went with an vintage German relay from Ebay since I've read that many of the new ones fail quickly, especially the ones from Brazil



For the VW relay pin 30 is wired to white (switched battery), 56 goes to the headlight switch in the shell, 56a goes to HB on the bulb and the HB indicator lamp, 56b goes to LB on the bulb, and S goes to the second relay.



on the generic SPST relay 85 and 87 both go to ground (I used a tab in the headlight shell), 30 goes to S on the VW relay, and 86 is wired to the blue/white wire from the right side handlebar switch

Clever, I'll have to chew on its circuits and function to see if I might want to adapt your idea. On bike I'd be interested to do it, the chassis is neg ground not positive earth, may be simpler?

hobot said:

Clever, I'll have to chew on its circuits and function to see if I might want to adapt your idea. On bike I'd be interested to do it, the chassis is neg ground not positive earth, may be simpler?

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naaah, unfortunately not, polarity does not matter with electromechanical relays like this (it does with solid state "relays" though)

Oh ok I was confused d/t mixing up ThunderHeart micro solid state harness gizmo and my own 6 relays set up in last late great Ms Peel. Kill button, one tag stays off feature is something I must do some how.

hobot said:

Oh ok I was confused d/t mixing up ThunderHeart micro solid state harness gizmo and my own 6 relays set up in last late great Ms Peel. Kill button, one tag stays off feature is something I must do some how.

Click to expand...

This setup would do the job, the VW relay latches mechanically so it will stay off until the kill button is pushed again...in fact was thinking of doing the same for the kill button myself, might also make the bike more theft proof (though a thief might push the right button at some point when trying to start the bike of course). Don't think the stock kill button would work though since it is NC IIRC, need to use an NO button but could be wired to switch ground so only one relay is needed....in fact I could have done this with the flash button but that would have required rewiring the horn so it was switched by ground too.

Thanks, I always like it went someone else does the deeper thinking i can use.