black/white wire to + on coil. What is it?

[FJB7340]

I cant find it in the diagrams I have. I've got a 6/73 40 and I just put in a pertronix ignition and coil. On the old coil + was the wire from the ballast resistor, and a black/white wire that I cant figure out. On the - was the black wire from the dizzy.

I bypassed the resistor as instructed and ran the positive from the electronic ignition, and the black/yellow directly to the + on the coil. I didn't attach the black/white wire back in because I didn't know what it was, even though it was attached to the original coil and is apart of the harness. it runs fine, maybe a little sputtering but not anyting too significant (I think the carb just needs adjusting) but now Im curious, does anyone know what it is?

this picture with the new coil in, sorry didn't get one with the old coil.

 

[PWCO70crusier]

B/W runs from the starter to the coil and from the coil to the ignition switch...
http://www.globalsoftware-inc.com/coolerman/fj40/schematics/FJ40/1974FJ40/HaynesFJ401974.jpg

 

[FJB7340]

Thanks for your reply, I was thinking my 6/'73 model was still a model year '73 and not '74? The '73 schematics don't have the bw wire so thats why I was getting thrown off. Do I fall under the '74 model year?

'72/'73 Schematic
http://www.globalsoftware-inc.com/coolerman/fj40/schematics/FJ40/1972-73FJ40/Haynes1973FJ40.jpg

 

[Pin_Head]

It should actually be black/yellow stripe. It may be bleached. Peel back the insulation tape and check again. The smaller black yellow wire is the ballast resistor wire from the starter solenoid to the coil+. It is there only to improve starting in cold climates and without the ballast resistor, it is not needed. The large black yellow is the ignition hot wire from the key switch to the coil.

The real black / white strip wire goes from the start position of the key switch to the starter solenoid to run the starter.

 

[FJB7340]

I peeled back the tape and confirmed the colors. The black/yellow came from the ballast resistor and I hooked it straight to the coil +. I took it off this morning and hooked the black/white up thinking I had it wrong, and it wouldn't turn over. I switched it back and it cranked up. I let it warm up a little and tried the black/white again and nothing.

I have a black/white that runs to the starter from the key switch but that wire is a significantly larger gauge than the one to the coil, and the only other wire (besides the large black one to the battery -)to the starter is the black/yellow. So I think its hooked up right but I still don't know what this black/white wire is. When the engine turns over as I crank, it is certainly not as strong as when I was running points and the old coil in the dizzy. I'll try and hook them both up and see what that gives me. Thanks for the feedback

 

[Pin_Head]

Just to be explicit: you disconnect the original small black wire with stripe that connected to the coil + when you had your ballast resistor. It is not needed, but having it connected should not hurt either. We can quibble about what the color should be, but the ones I have seen are black with yellow stripe, just like it says in the FSM wiring diagram.

 

[FJB7340]

@Coolerman Yes, Im with you, that wire is black with a yellow stripe. I disconnected that wire from the ballast resistor and connected directly to the the coil+. You are saying it isn't needed but if it is connected to the coil then its not really a big deal right?

The thing Im getting hung up on is seemingly an extra wire that is not listed in the '73 diagram. The diagram shows only one "BY" wire from coil positive to the fuse panel.

(from '72/'73 diagram)

But I have two wires where one should be; the BY and an extra wire that is BW.

But its not too big of a deal i think because as it is, it seems to run just fine. So I guess its seeming like a PO may have put in a post '73 wiring harness at some point? Thats the only way I can justify having a BW wire there.

(from '74 diagram)

On another note, as you can see in the picture, my horn relay is pretty rusty and subsequently shot. I'd like to order one of your replacements. Ill send you a PM.