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Anyone out there done a 2G alternator conversion on their Slick?
Have a friend's 66 F-100 in the shop right now that has had a 2G installed (long story) and I am trying to sort out the bugs. Truck has a 351w with a Dura Spark ignition. Starts and runs decent, but won't shut off with the key. I have to unplug the DS module to shut it down. I have checked and tested the ignition switch and it is not the problem.
Looking at the 2G wiring it appears there is a light green wire from the alternator that goes to one side of the ALT light in the dash. The other side of the ALT light comes from the ignition switch, supplying 12 volts to the light with the key in the "on" position. Looks to me like the alternator is supplying power to the ignition switch, through the ALT light with the key in the "off" position, allowing the rig to continue to run.
Has anyone here experienced a similar problem with a 2G conversion? any thoughts or suggestions would be appreciated.
I'm not totally familiar with that alternator. But in the factory wiring for the Ford alternator the wire for the Alt. light is used to excite the field. It runs from the "I" terminal on the regulator to the light then to the ignition switch, that circuit also has a 15 ohm resistor wire in it that is wired in parallel with that light. They are connected to the center post on the ign. switch. That way if the light burns out the regulator is still getting power. If they connected that green wire from the alt. to that Grn/Red wire that was originally used for the Alt light it should work. That grn/red is on a two pin plug by the horn relay paired with a yellow wire.
I don't envy you having to figure out someone else's wiring.
Thanks for the response.
The 2G alternator was an early attempt by Ford to go with an internal regulator. On the '66 I am working with, the stock regulator and ALL associated wiring was removed before I got the rig. I did locate the two wire plug you are referring to and proved out the wiring. This is where I connected the light green wire from the 2G to the green / red wire at this two wire plug. The underdash wiring has been "reworked" as well, but I was pretty sure I had got it back to "factory". I will have to check on the resistor you mentioned I don't remember seeing it anywhere in the circuit. Will also have to confirm where the 12 volt ignition "on" source for the ALT light originates.
The power originates form the center post of the ignition switch that would be the Blk/Grn wire that shows up in several places in the harness. Here are a couple of pictures of an original harness.
The first pic is the firewall plug the black wire paired with the yellow wire is the resistor wire it is very long and is taped in the harness.
The second pic is the other end of the resistor wire paired with the Blk/Grn on the center stud of the ignition switch.
Why Ford changes colors at connectors I have no clue but they do.
Hope this helps.
One more thing. If you remove the bulb and disconnect the green wire without power on the system your ohm meter should read 15 ohms across the blub terminals if the resistor wire is there and good.
I really appreciate the pictures and additional information. Every little bit helps and we all know what they say about a picture.
I haven't been back out to the shop today, and most likely won't until tomorrow. I will post my findings then.
I don't know if this is your fix...but, I have done a few alternator conversions on older, generator equipped vehicles. The guy I get the 6 volt alternators and brackets, 5th ave internet garage, sells what he calls a "DA plug" that keeps the anternator current from backfeeding through the ignition switch to the coil, causing the engine to keep running. I believe that it is nothing more than a one-way diode installed in the exciter wire.
HTHY, Dan.
65 F100 lwb 352 3 on tree
63 F100 lwb Restomod project 5.0 T5 Fox body front clip
What you describe sounds like the problem I am having and I hope to check it out further a bit later today. Between your comments and those of Crop Duster I hope to resolve the problem. I will post my findings once I find the problem.
I had a chance to spend some time working on the '66 yesterday. Had a couple other issues, none electrical, that needed to be addressed first. Was able to check out some of the wiring, specifically what Crop Duster had addressed. All of that looks to be intact and in decent condition. I plan to start trouble shooting the underhood wiring tomorrow.
I did check out the DA plug that Thunderkiss1965 mentioned. Not real sure that I will need to go that route, but as for now everything is still on the table.
I finally found the problem. Whooppee! It didn't have anything to do with the 2G alternator, resistor wires or back feeds. I have to admit that I spent way more tine than I should have to locate the problem, but...
I found that the wires that go to the 2 prong plug at the Dura Spark module were crossed. The plugs both have a red and white wire, and vehicle wiring was connected as such. After taking a step back and looking at things I saw the plugs had opposite polarity, that is the red connected to the white and the white connected to the red. Straightened this out and all works as it should.
I want to thank both Crop Duster and Thunderkiss 1965 for their input and suggestions. While the fix went in a different direction than I originally thought their comments were very helpful in troubleshooting, and eventually correcting, the problem.
