Here's the original thread when this topic first came up.

https://www.ford-trucks.com/forums/8...on-module.html

 

That is an interesting thread.
It would be a HUGE help to me at this point if you or someone else could tell me what actual wires or poles these three wires on the 75 module are hooked to.

The diagram indicates the #4 Red wire goes to "R" on the switch. Would that be the "Ign" pole with the resistor wire?

And where does the #5 White wire actually hook into the system? Is it the "I" pole of the starter relay?

And the #6 blue wire, it seems to hook into the red/green wire that goes from the resistor wire to the + side of the coil. Is this correct?

I'm just having some trouble deciphering and following the diagrams, and any help is appreciated.

 

Red to run, white to start on module from ign switch. The resistor wire is in place to drop voltage to the coil. Full 12v will overheat coil. The blue wire was to retard spark during startup and removed on later modules. In start, full 12v is applied to solenoid on "S" term and runs back thru the "I" term to coil in start position only. I can wire these things almost blindfolded, explaining it is not my strong point. Only problem I ever ran into was the red and white wires were swapped in the connector itself which will cause the engine to fire and shut off as soon as in run position.

 

OK, so red goes to Run on ignition switch, white goes to Start on Ignition switch.
Where does the blue go?
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It's the white wire that retards timing a few degrees during startup, not the blue wire, the blue wire is some sort of electrical shunt.

 

That seems to make sense, since the white wire does go to the Start pole of the ignition. But what about that blue wire? On gwf's drawing it looks like it goes to the I post on the starter relay. Am I right about that?

 

I found this old post on another forum, very same scenario that i encountered a few years back, but once again, no explanation is offered as to why the revised 6-wire modules will not work.

&bull; View topic - ignition module help

 

I think the the 6 and 7 wire modules don't work for this reason:
Wiring diagrams for the '75 system show R, R, and S (Run, Run, Start) as the three points on the ignition cicuit that these three wires go to. But, the diagram for the 76 system shows S, R, S. What you will notice is that on the 75 system the white wire (#5) goes to R, but on the '76 system it goes to S. So, I think the 2-wire harness could be used, but it would have to be tied in to different points on the system. It's not just a matter of unplugging the 75 harness and plugging in the 76 harness. In other words, the parts catalogues are right when they say the 2-wire can replace the 3-wire. They just don't tell you that you need to modify the setup to do that.

That said, I have a 3-wire module for my '75, but my problem is that I don't have the harness that it plugs in to on the truck, so I need to run wires from the harness to those connection points, and I can't figure out where the blue wire actually goes to on those systems that have it.

 

No, this is not the reason. You are getting confused because of a very comon irritating problem that's not your fault.

Someone in the aftermarket parts sector, or at Ford, sometime since these trucks were Factory built, made a huge mistake and switched the Red wire for white, and white for red.

This affects all Duraspark modules. DS-I, DS-II and DS-III.

So as a concequence of this blunder...

The aftermarket wiring diagrams are wrong and get the Red and white wires reversed.

What's even worse, aftermarket modules and some motorcraft replacement modules, and even aftermarket replacement wiring like painless, switch these Red and white wires around as well.

So this is what you need to know.

Wire colors with factory installed module and factory wiring, and using Ford Diagrams:

1: RED (Can also be Red/Blue stripe) wire: START
2: WHITE: (Can also be White/blue Stripe) RUN

Replacement Aftermarket and certain replacement Motorcraft Modules, Aftermarket wiring kits and aftermarket wiring diagrams.

1: WHITE: START
2: RED: RUN

Here is a picture of a replacement module with the reversed colored wiring, hooked into the factory wiring harness. See how the colors swap at the connector.



The connector is idiot proof, so if the wires cross like this, DO NOT make them match. The colors of the wires are crossed. NOT their function and where they need to connect.

So not only do you need to know if your truck has factory installed equipment of replacement equipment since the truck was manufactured. You need to know if you are using Ford diagrams or aftermarket ones too.

 

Well, that's an important bit of info, to say the least. Thanks for that. I am certainly using an aftermarket module. My truck does not have the harness into which to plug the module, so I guess I need to run wires from the module harness to where they need to go. In my case, White to Run and Red to Start retard. White to Run is simple enough. Is Start retard the "Start" pole on the ignition switch?

 

The same wire goes to the starter solenoid S terminal. Notice how it is RED/BLUE as well at the starter solenoid. This will go to the start retard function on your Duraspark module. Most likely white on an aftermarket module.

I highly recommend getting a harness or at least the idiot proof connector out of a junkyard somewhere. It's so easy to wire these wrong because of the problem I described earlier, it isn't funny.

 

I'd love to have the factory truck harness as you suggest. I have access to a few good junkyards where I am, but it's hard to find one specifically for the 75, and lots of those places will not take or keep the older vehicles. Maybe I will rummage one up soon.

Meanwhile, your most recent info is a huge help, and makes sense given the red/blue on the starter relay. Now I just need to figure out where on the vehicle to run that blue wire to and I may be in business.

Thanks again.

 

Well, I got her running. Ran the red wire from the module to the Ignition pole of the ignition switch, tied the white wire into the red/blue wire running from the S side of the starter relay, and tied the blue wire to the green wire with red tracer stripe that goes to voltage regulator (just like in the 1975 wiring diagram I posted earlier). It turned out the pick-up coil was shot, so once I replaced that and got the wiring sorted out, she was good to go. Thanks everyone for all your help.

 

Thanks for the update, glad you got it running.

 

Thanks for all the help on this, all I had to do was read the posts and I got it running, all though it was only for a bit before the carb clogged. I pulled the carb off and rebuilt it, but noticed that there was no idle screw, any ideas where I could get one? At first I was surprised it would even run without one, but then noticed that the RPM’s were so low the alternator wasn’t even charging the system. With a few “in the field” modifications, I was able to get it idling where I wanted it (mostly), but would much prefer the correct part. Another thing I found out was I flooded it once when it was buried up to the bottom of the door and it stalled, but when I tried to crank it, I could hear the starter motor turning, but it wasn’t popping over and hitting the gear to turn the engine. Do I need to rip it off and RTV all the fits to keep the water and such out?