I'm straightening out an electrical mess and the schematics I've downloaded are not right. This truck had an electronic ignition, its' wiring has been abandoned, burned and 'improved' on. It now has a Mallory ignition with box and Unilite. The original factory harness is different than the schematics, granted the harness has had wires snagged into it and been properly abused but there is enough of it for me to see what is original and what isn't.
For instance, the brown wire from the odd side of the solenoid that the schematic shows going to the coil to back feed during the 'Start' mode, this wire is now running back inside the cab in the harness entering near the glovebox. The schematic show points ignition with that brown wire terminating there, the truck has connectors for the Ford electronic ignition box.
Any advice? Did Ford offer both types of ignition? Are there better schematics available?
Thanks, OJ btw, V8 Bronco.

 

Yes, Ford offered both ignitions that year based on where it was delivered.
CA trucks got the electronic Duraspark that still had the small distributor cap (just like on a points distributor) and Fed trucks got the points for another year.
I think some CA trucks even had catalytic converters, but pretty sure Broncos didn't get them until '75 when all CA vehicles had to have them. Maybe even all Fed vehicles too.

My Haynes show's '74 with electronic ignition, while the Chilton's lumps 73 and 74 together with points.

Paul

 

If you can't find the Hayne's '74-specific diagram, you might use '75 as your basic reference and just assume you might still find some oddities here and there.
In other words, trust but verify!

Your Brown wire sounds correct. For '71 Ford started running all the wires into the cabin and then to wherever they needed to be. Rather than the practice of running them all across the passenger side of the firewall to behind the engine.
So your Brown wire would go into the cabin, then come out behind the engine to the Red 3-wire(?) connector at the driver's side valve cover where it becomes one with the Red w/green wire to power the coil.
On some at least, you can actually see it join the wire there at the body side of the connector. I would guess that on some it's spliced in under the dash where you don't see it.
Ford made lots of tiny little changes over the years. Even those that the diagrams don't show.

A good example of the disconnect between diagrams and reality is the '71 diagrams being lumped in with the '70 and earlier models. Presumably the aftermarket manuals used outdated diagrams and never got the '71-specific version until after printing. Or not at all maybe.
But '71 was more like '72 than it was like '70, so those owners need to use the later one. You might as well, but if you can find a Hayne's book that's even better.

The one with the blue cover is kind of half-useless in my opinion. If you can find the brown cover version covering the '73 to '79 trucks, that would be the best.

Paul

 

Thanks Paul, your explanation of the brown wire makes perfect sense and I know the red connector you speak of. I weeded out and eliminated the unnessary wires that were in the harnesses, the worst was the one from those three connectors (including the red one) running behind where a chevy distr would be, they had shorted at some point and all those wires were kinda joined together inside the tape. The brown wire would have been included.
Here was my puzzle. The truck now has Mallory ignition box, Unilite Distr and the box feeds the coil. That mess from the burned/joined supplied the box 'ignition' circuit with what would have been the ignition 'run' wire (rd-gn), when I tested it the initial voltage was 7.9 and a few seconds later it'd go to just under 10volts. It did this repeatedly, I never tested it for 'Start' voltage. I redid parts of the harness - I still didn't know about the mess under the tape - and the 'run' voltage cleaned up to 12.25v. I then cleaned some wiring up under the dash and that must have affected the wires going thru that burned harness because I lost my 'Start' voltage. Until then I didn't know how the 'Start' voltage was present, it was a mystery to me because only the 'Run' wire was visible. Thanks to your explanation the 'Start' voltage was coming thru that Red connector and worked because all those wires were melted together inside the harness! It was working thru the rd-gn 'Run' wire, thye had to be melted together!
Thanks again, mystery solved.

 

Cool. Going to a lot of work there, but it should all be worth it in the end.
When you say you lost your START voltage, do you mean through the Red w/blue wire to the starter relay's "S" post?
If so, it might have been when you were messing about in that same area behind the engine. In '74 whether your truck came with an automatic or a manual trans from the factory, there will be the same 4-wire black connector back there. If you have an auto it will be connected to the neutral-safety switch. If a manual, it will have a simple jumper for the Red w/blue wire.

This jumper will simply look to be a loop of Red w/blue wire just going from one side to the other, next to the two Black w/red wires..
The Blue w/red jumper is so you can start without the neutral safety switch.
The Black w/red wires are your backup lights.

If you pulled that connector and did not re-connect it, or if you cut the loop for some reason, or it was just damaged during the moving about (common break point actually) then you won't have anything going to the starter relay to tell the starter to spin.

Paul

 

Sorry about the confusion, it was the voltage back feeding the coil during 'Start'. The motor would spin but no ignition power from the brown wire, it had burned up inside a harness and I eliminated the harness entirely.

 

No 1974 truck, Bronco or Econoline came with a catalytic converter.