Euro Light Switch Wiring

[jforgo]

Help, o sage ones!
Since the turn signal part was dying anyway, I got the replacement left side switch which includes the headlight switch for my 1982 r100rt. But I cannot tell from my otherwise lovely Clymer color diagram how it connects.
Anyone have this info - or done this?

 

[20774]

From Haynes, for the headlight switch:

56b - yellow - goes to 56b in headlight shell
56a - white - goes to 56a in headlight shell
30 - green - goes to 15 (fused) in headlight shell...other side should be green with black wires
56 - yellow with white - goes to 87 on light relay in headlight shell

For the horn:

50 - brown with white - goes to H in the headlight shell
85 - green with black - goes to 15 (fused) in the headlight shell

For the signals:

49a - green with yellow - goes to 49a on the turn signal relay
L - blue with red - goes to L in headlight shell
R - blue with black - goes to R in headlight shell

I don't see anything on the diagram that says "UK only".

 

[jforgo]

thanks - that gives me a good starting point

the Clymer only has some "USA only" lsted for a bit of 90's stuff . Now I am wondering if the tail end of the existing "light-switchless"control already has all the wires. I don't know yet, because I don't like tearing into things if I do not have my ducks in a row.

 

[FELAW]

euro switch

I think Kurt is right about the wiring scheme. I did the installation last year and found 11 wires from the switch instead of 9, leaving two extra. They're for the parking light inside the headlight which isn't there on the RT (its on the eyebrow). I installed one anyway with a 20 w bulb. On the park switch setting, I have both the eyebrow and the small running light inside the headlight on. It took a bit of work and the details are in a post to a similar thread a few months ago.

 

[jforgo]

More info

OK, additional info:
The Euro switch has additional wires from the new light switch piece:
Green, Grey, and Green/Orange
On the headlight end the Green is joined with another to one terminal. I believe the other Green is associated with passing switch.
Interestingly, the old Green wire was connected to "Reserve" rather than 15.
Nonetheless, this leaves me with extra Grey and Green/Orange wires - where do these go?
The Green/Orange has a straight, rather than right angle, termination, so I am thinking it must go to a relay. Replace the black lead from the starter?
The Grey has the angle connector - to the second fused area? Right now that only has a double Grey/Black to it.
Anyone know where the Green/Orange and Grey wires go? I am unsure about just playing around with theses wires.

 

[lkchris]

It's really easy to wire one of these up, as most of the colors are the same on the terminal board in the back of the headlight as the colors of the wires themselves.

To create constant-on headlight--as your bike came to the USA--there is one short wire from the terminal board direct to the headlight relay. This wire is clearly replaced by wires in the new switch, the angle-connect one to the board and the straight-connect one to the headlight relay.

The park/tail lights are usually turned on by the headlight relay, but that's only activated when headlight is turned on. For the new switch to activate park lights, new wire is included to go to the circuit board. There will be a spare terminal for this.

There's one additional thing you need to complete this installation, and that's a new--different--headlight relay. Best way to get one is to ask for headlight relay for a 1977 model. If you don't replace the relay, you'll find in some instances that running the starter motor actually turns on the headlight. It wires up the same way and fits in the same location--it just has different internals, i.e. diode.

It may also be fun to know that the headlight relay in these bikes does not exist to "protect the switch" but rather to ensure separation between the park light circuit controlled by the ignition switch and the same function when controlled by the handlebar switch.

 

[jforgo]

The Black wire from starter relay to light relay appears to only exist for lights on 1978> models. Wouldn't disconnecting this obiviate any problems about the starter to light interference? Or could doing so mess up the starter relay?

 

[FELAW]

wires, wires, wires

The green/orange ( or green/xxx) is the low beam switch wire . I connected it to the yellow wire coming from the headlight bulb, bypassing the yellow section on the terminal board.. both are female connectors so I clipped the green/orange and added a male connector.

As you pointed out the green wire is duplexed in the euro set up. It replaces the single green that went to the reserve section on the center of the terminal board (this section only has power when the key is on). 1 wire powers the headlight switch itself and the other the horn, which was powered by a jumper wire inside the old handlebar switch.

Oh yea, the grey wire powers the park/running light on the headlight reflector. The RT's dont have this bulb( you'll have a little plug in there instead) . The RT running light is on the eyebrow. You can just tie the grey off and not use it or, as I said in a prior post, put in a bulb and socket and run a ground to the brown area on the board. This way, you get both the eyebrow and the headlight running light on when the switch is in the park position.

 

[lkchris]

The Black wire from starter relay to light relay appears to only exist for lights on 1978> models. Wouldn't disconnecting this obiviate any problems about the starter to light interference? Or could doing so mess up the starter relay?

Even when there's a Euro switch, there's the possibility of starting when the headlight is on, and when that occurs you want the headlight to temporarily go out. That won't happen, of course, if you disconnect this wire. (It couldn't hurt the relay, of course.)

Best bet, again, is to get the '77 headlight relay as it's what was installed on actual Euro bikes that actually came with the Euro switch and it's simply the required "part two" of the conversion of the USA model.