truth Posted February 9, 2016 Share Posted February 9, 2016 i included photos of the switch in question it is right beside another switch on my 1918 fiat switch that is a bosch dual coil switch the bosch dual coil switch allows you to start on battery then switch to magneto the switch in question though is the 5 pictures as you can see it only has one wire out the back yet the switch has 2 positions? i believe the one wire will work only when there is a ground since it is a wood dash i think the ground is attached to one of the 3 monting screws[one hole is tapped w threads] so i understand how one function can occur through this switch. my confusion is why the 2 different selections and whats it for? some kid ripped all the wiring out this car and im trying my best to figure it out! i know there is an answer out there can anyone help me? theres a #1in the center then a # 2 on either side then a #3 on the handle in the center above the #1 is stamped "dual" the very top on the curve is a riveted plate that says bosch Link to comment Share on other sites More sharing options...
maok Posted February 9, 2016 Share Posted February 9, 2016 You generally don't go to 'earth' after a switch. Those two screws on the back maybe the output of the switch to turn on whatever. Link to comment Share on other sites More sharing options...
Spinneyhill Posted February 9, 2016 Share Posted February 9, 2016 Headlight dip and high beam, with off in the middle? Or perhaps Off, left is cowl lights, right is headlights? Link to comment Share on other sites More sharing options...
Restorer32 Posted February 9, 2016 Share Posted February 9, 2016 Magneto cut off switch? 1 wire to switch from mag that grounds when the switch is "switched" thereby cutting off the mag? Link to comment Share on other sites More sharing options...
Restorer32 Posted February 9, 2016 Share Posted February 9, 2016 Nevermind. I just realized it has 3 positions. Link to comment Share on other sites More sharing options...
emjay Posted February 9, 2016 Share Posted February 9, 2016 One thing to do is to check what has continuity and what doesn't for each switch position. The screws on the back just look like housing retention even though the spacing is odd. But go ahead and probe those in the different switch positions and not just to the terminal but to each other and the case. Link to comment Share on other sites More sharing options...
truth Posted February 9, 2016 Author Share Posted February 9, 2016 i will do continuity when i get home tonite ive done it once and all it does is one function on and off the #2 positions are the same but i will check some more i like the idea of magneto cut off cause how else would the car turn off? i guess you could flip to either of the 2,s to turn off?i think the lights are on push button switches some of the wires are there for some of the lights the stamp of dual kinda makes me think its related to the ignition system its new to me though that you can flip 1 switch to 2 different positions and it does the same thing why would fiat do that? thanks for your comments ill post definite continuity results Link to comment Share on other sites More sharing options...
emjay Posted February 9, 2016 Share Posted February 9, 2016 Put Bosch dual magneto switch in your search engine and some interesting images are available very similar to yours. It appears the left 2 should be a 0. This is a link to a pdf that came up on the search, which should help you and it does look like the screws are terminals.restorecarsclassifieds.com/wiki/show_pdf.pdf?n=379 Link to comment Share on other sites More sharing options...
emjay Posted February 9, 2016 Share Posted February 9, 2016 (edited) I had a chance to study the pdf and the top diagram look very appropriate for your switch. Left is off, center is one set of plugs and right is both sets of plugs. Looking at the back of your switch there are faint circular marks on the same diameter as the 3 screws. Missing terminals? Probably time to ease the cover off the back. Edited February 9, 2016 by emjay (see edit history) Link to comment Share on other sites More sharing options...
Layden B Posted February 9, 2016 Share Posted February 9, 2016 This switch is peculiar to 2 spark dual Bosch magnetos. 2 position ( both left end and right) is for both sets of spark plugs in operation, 1 position is for just one set, use this for starting then switch to 2. Why Bosch made this a 3 position switch is beyond me! Link to comment Share on other sites More sharing options...
Layden B Posted February 9, 2016 Share Posted February 9, 2016 Link to comment Share on other sites More sharing options...
truth Posted February 10, 2016 Author Share Posted February 10, 2016 wow yall are great! alot of info that ive been starving for thank you ive got to digest this it sounds like both sets of plugs may be used at same time? i thought one set was for start on battery then switch to magneto[which is done w the bosch dual coil switch not this switch] but im starting to think theres more to it i took the switch apart and did continuity all the #2,s do on the switch is interupt the signal the signal goes through switch in # 1 position[the brass button is the wire connection on the back side you can see where the switch travels by the skidmarks in the bakelite non conductive material] ill post again once i wrap my little brain around all this and thanks again Link to comment Share on other sites More sharing options...
60FlatTop Posted February 10, 2016 Share Posted February 10, 2016 (edited) It's hard when someone removes parts that would help you sort the system out. Is there evidence of a glass jar battery mounted on dash or under the passenger seat? That may be independent of the electrical system and the charge maintained by a charging plug connected to a charger in the owner's garage. That would be the power for starting on the coil ignition. Once started the switch would be positioned to turn off the coils and their plugs, then switch to the magneto. I wouldn't expect it to run on the coil and mag concurrently. Sometimes you just have to mount the pieces in place, start with what you do know and build on that.I am not familiar with the Fiat. Does it use a generator or flywheel mounted dynamo? Is there an oil filled switch with a mushroom foot pedal to start? Two 12V batteries in series?I am being reminded of a 1913 Rambler that I sorted out electrically about 20 years ago. And wondering if you have taken a look at electrics on some of the early Rolls-Royce small horsepower cars. You might get some answers there.Bernie Edited February 10, 2016 by 60FlatTop (see edit history) Link to comment Share on other sites More sharing options...
JACK M Posted February 10, 2016 Share Posted February 10, 2016 My old V 12 fire truck ran its best with both ignitions on at the same time. Link to comment Share on other sites More sharing options...
truth Posted February 10, 2016 Author Share Posted February 10, 2016 this 1918 fiat touring has a 6 volt battery on the running board its housed in what looks like a big tool box theres 2 holes drilled in running board apron for cables to go through im thinking[and yall can correct me ] that the switch in question stays in #1 position when car is not running this grounds out primary circuit to points for the mag when you start car the bosch dual coil switch is in battery and start selections once it starts you put those switches into mag and run positions then flip switch in question to one of the 2 positions labeled#2 this stops the primary circuit being grounded and now all 8 spark plugs are firing in all 4 cylinders[ 2 per cyl] im still not sure how to shut it down cause the battery and coil will still be on after the switch in question goes back to ground[ or position#1] maybe the off on the other switch is when the selection is in center between batt and mag if thats true i may have arrived w everyones help im getting closer thats for sure and seeing lite oh this does have a generator but im thinking of just keeping a small tender on it and not using the generator cause of other issues and im pretty sure its positive ground i think once the bosch coil switch is put on mag and run selections that this turns off the coil so starting to make some sense of it i think for now Link to comment Share on other sites More sharing options...
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