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General Category => General Discussion => Topic started by: lazlokovacs on April 14, 2016, 04:15:01 AM

Title: 71 eldo loop speciale headlight query
Post by: lazlokovacs on April 14, 2016, 04:15:01 AM: my headlight CEV replica switch keeps shorting out and melting the plastic... I have a vague memory of someone in the guzzisphere posting a fix for this, something to do with adding a relay? Can't find it searching the forum the though...

anyone in the know?

thanks as ever
Title: Re: 71 eldo loop speciale headlight query
Post by: Zoom Zoom on April 14, 2016, 05:12:57 AM: Basically, you would use the switch to trigger the relay. To avoid cutting or otherwise damaging the existing wiring, you would run a couple conductors, (wires) from the headlight bucket to a location where you would mount the relay. One would pick up the power lead from the headlight and that would be used to power the relay. You would use the other wire to go back to the headlight bulb. You also need a power wire from the battery, fused, that the relay will "cut through" to power the bulb. Also a ground wire is needed on the relay.

So, relay power and ground. Power in from battery and out to headlight. Relays have standard numbering that identifies the pins. Don't recall what they are at the moment.

Does that make sense? It is easier than it sounds.

John Henry
Title: Re: 71 eldo loop speciale headlight query
Post by: Cam3512 on April 14, 2016, 05:21:12 AM: Email Greg Bender. He sells the kits.
Title: Re: 71 eldo loop speciale headlight query
Post by: Markcarovilli on April 14, 2016, 08:39:37 AM: Quote from: Cam3512 on April 14, 2016, 05:21:12 AM
Email Greg Bender. He sells the kits.
:1:
and check out his site at www.thisoldtractor. com

Mark
Title: Re: 71 eldo loop speciale headlight query
Post by: Antietam Classic Cycle on April 14, 2016, 08:44:10 AM: +1

http://www.thisoldtractor.com/for_sale_wiring_harness_loop.html

The "Relay Solution". About half way down the page under "Custom Sub-Harnesses".
Title: Re: 71 eldo loop speciale headlight query
Post by: Kiwi_Roy on April 14, 2016, 10:06:44 AM: I think this schematic is probably close to your bike
http://www.thisoldtractor.com/guzzi007/schematics/1973_V850_USA.gif

You need a pair of relays, I like to use the Bosch cube style because they are period correct and have a mounting tab, mount these in the headlight bucket or close at hand.
Disconnect the green and Green/Black wires from the dimmer switch and put one to the 85 terminal of each relay, the 86 terminals are wired to chassis or black wire. So now the dimmer switch is picking up one or the other relay. Wire the bulb Hi / Lo filament to the 87 terminal of the relay (don't worry which one), all you need now is a source of 12 Volts to the 30 terminal of both relays, this can be the same fuse that feeds to the dimmer switch (Grey/Red I think) or you could run a new supply from the battery.
If the dimmer switch operates the wrong beam swap over the wires on the 87 terminals or the wires on the 85 terminals and it will work correctly.

I like to add a 40 Amp main fuse to my bikes right at the battery, this protects the feed to the ignition switch and Voltage regulator. The fuse also means you can safely tap into the large red wire at the ignition switch, I use that to feed headlight relays by-passing the ignition switch, another source of Voltage loss on an old bike.
The headlight will operate as before only brighter.

You might also consider adding a relay to the horn while you are about it.