850 Le Mans high beam flash wiring question

[Rafael]

I've been studying the wiring diagram for the 850 Le Mans in order to clean up a aftermarket left control switch installation. The new switch ( looks the same as the european Quota ). Most of the connections are straight forward but I can't seem to firure out the stock hi beam flash operation. The button when depressed, grounds out at the handle bar and draws power through a 3 point relay, but the relay seem to send power over to the low beam. Can anybondy explain this set up to me?

I'm sure I can get the hi beam flash to work, the new switch operates completely different from the old one, it diverts power from the low beam power source. I'm mostly curious.

thanks

[Series4]

The 850LM flashes low beam only, high beam is only switched by the headlight switch. When park or high beam is selected the flasher will flash but it won't work on low beam

[Sahms]

The 850LM flashes low beam only, high beam is only switched by the headlight switch. When park or high beam is selected the flasher will flash but it won't work on low beam

I used the generic left-side switch block MG Cycle sells, and on my LM the high beam is triggered by the Flash, and the high beam indicator lights as well.

I used the Euro CEV switch from 1993 or so on my T3 (same wiring) and it works the same way.

[Rafael]

thanks Peter, makes sense it terms of the diagrams, I can see why MG changed that soon after. All MGs with that switch probably function the same way. I must of gone thru this 25 years ago when I updated my T-3 to the early '80s MG switch found of the SP-NT, guess my memory for little details don't go that far back

Anyway, the only remaining item I haven't figured out is the parking light position on the new switch. It doesn't provide a separate wire for this function. I probably end up wiring it along with the low beam... but it does have a spare wire maybe I can connect it internally to the parking light position.

[Rafael]

Hi Sahms, you posted about the same time I did and didn't see your reply.

It's not that I couldn't wire this thing up to flash the H beam. I was just having a brain fart and unconsciously couldn't believe that the L beam is connected the the flash button. There's probably a scientific name for that - being blind to what the evidence is telling you.

How did yo hook up the parking light circuit to the MG Cycle switch?

thanks,

[Sahms]

Hi Sahms, you posted about the same time I did and didn't see your reply.

It's not that I couldn't wire this thing up to flash the H beam. I was just having a brain fart and unconsciously couldn't believe that the L beam is connected the the flash button. There's probably a scientific name for that - being blind to what the evidence is telling you.

How did yo hook up the parking light circuit to the MG Cycle switch?

thanks,

I had a lens/reflector with the cute little pilot bulb, so I really wanted the park circuit to work.

The switch has the position, but the wiring diagram on the package doesn't call it out. It was relatively simple, but it's been a while.

I found this:



and:

[Rafael]

thanks for the diagram Sahms, I compared it to what I came up with.

The parking light circuit (+) is in position 7, which your diagram shows "Blank". But you show the switch Blue wire connecting to position 10 (-) which is energizes the parking light circuit from the head light (+) circuit by the new switch. Since position 7 is unconnected that means that your parking light circuit setting on your ignition key should not work - please confirm. I wonder what connecting the RED wire in position 7 to position 10 will do? I'll try it, tracing wires on the diagram is crossing my eyes!

So, since your used the Blue switch wire marked as "Blank**" on the manufactures' diagram is actually the parking light circuit energizer (-). I'll test it soon to confirm.

thanks,

[Rafael]

All wired up. Sahms, thanks again for the diagram. Tested all function work as indicated by control. And my suspicion was right the parking light position on the ignition switch doesn't work. I don't think its worth the effort putting a jumper wire in between connector block position 7 and 10. I've never used that setting anyway. But I'll test it tomorrow.

Update:

The separation of two positive currents used for the headlights and parking lights are accomplished by the OEM switch. With the aftermarked switch, a connection between the two positive feeds would be have to be made at the Molex connector as stated above. Light switch would function normally with the ign. key in the RUN position but the parking light feed would end up back feeding the head light circuit when in the Park position. So you would be able to turn the head light on. Again not worth it.

[fossilrider]

I hate to keep going on about this (and hate even more to look stupid!) but how exactly do you mean to connect a ground wire into the harness? Like I said,everything else is working so I assume I have the rest of the hookups right.That said,I do have two more things that don't make sense to me;one is the red/black wire in the harness that is hot isn't hooked to anything and the yellow wire and the plain red wire in the harness (also hot) I have hooked to the red/yellow wire from the new switch.I don't think any two wires in the original setup were connected to a single wire.Anyway,whatever I've done,all seems good if I can just get the horn button and the starter button to work.The "passing flasher" light button works too.Oh yes,my turn signals all work but flash what seems too fast to me.?Thanks,Fossil

[Rafael]

No worries, no Qs are stupid.

Notice the two "Added ground" on the block diagram above by Sahms. They were added because the new switch grounds through the dedicated wires to the harness Molex wire connector (while block) where as the old switch grounded directly to the handle bar at the switch. So you need to connect these two wires to a empty positions on the 15 point Molex, then add a ground wires to the new position on the back side. IIRC, the T-3 grounds inside the headlight bucket. Make sure the ground wire to the bucket is grounded properly.

If you haven't already found a source for the Molex pins, you can find them at Radio Shack, buy a 4 point connector to swipe the pins from.