Replacing Excitor wire with Copper & Resistor

[Beach_Dude]

Beating this dead horse but no actual diagrams to demonstrate placement.

1977 Jeep Cherokee w/Motorcraft Alternator and Regulator

All new and custom wiring harness with original placement, except for slight modifications and I really want to nip this pulse in the keister.

Which line was the original exciter wire, which is now going to be copper with proper resistance?

Point A, B, or C?



Point A seems that it would lower the charge to the battery.

Point B seems that it would be proper placement given that it bypasses the battery charge and adds resistance to the regulator, which would excite the alternator.

Point C Seems to lower the overall power to the entire system, which could benefit the system to not overcharge, blow fuses/burn out bulbs, etc.

Anyone familiar?

[JeepJeepster]

I shouldnt reply since idk the in's and out's of the 77. Its certainly NOT C.

It may be the wire coming right out of the alternator field terminal.

You dont need the resistor wire. You could just put a diode in.

[Beach_Dude]

Spoke with a knowledgeable guy that's redone a few broncos and has knowledge on the Motorcraft alternator and charging systems.

Obviously the Jeep system is WAY off, but after going through the wiring diagrams with him, he said Point B seems to be the most logical, giving the battery the higher boost while engaging the alt.

And the verdict is I don't know if it's really charging or not now... LMAO

So, it's steady, and at 0, unless I turn everything on, then it drops to about -10. Also, an old problem of lowering the tailgate window now shuts off the stereo meaning there isn't enough juice to keep the stereo on. It appears as if Point B actually dropped the entire system down to like 5V... crazy!!!

I ended up trying a 3Ohm resistor now, and everything seems pretty stable. Also, I bought a bunch of new connectors, including the voltage regulator connector. Tomorrow I'm going to add a bunch of disconnects to the leads and experiment with connecting the black wire (43 Black 16).

Will keep ya guys posted!

[tgreese]

The Motorcraft alternator does not use a resistance wire, according to the wiring diagram. The field connection where the exciter current goes comes from and is under the control of the regulator. The resistance wire is a design feature of the Delco alternator. The Delco needs this extra component since it uses a single wire to provide on/off and exciter current.

If I were going with a new harness, I would get rid of the unreliable and less common Motorcraft alternator and regulator and use a Delco 10SI. The Delco app is shown on your '77 diagram, since the 232s and 258s got the superior Delco alternator in 1977. The resistor is clearly seen in the Delco part of the diagram.

[serehill]

Originally Posted by tgreese

The Motorcraft alternator does not use a resistance wire, according to the wiring diagram. The field connection where the exciter current goes comes from and is under the control of the regulator. The resistance wire is a design feature of the Delco alternator. The Delco needs this extra component since it uses a single wire to provide on/off and exciter current.

If I were going with a new harness, I would get rid of the unreliable and less common Motorcraft alternator and regulator and use a Delco 10SI. The Delco app is shown on your '77 diagram, since the 232s and 258s got the superior Delco alternator in 1977. The resistor is clearly seen in the Delco part of the diagram.

Couldn't have said it better.

[Beach_Dude]

The thing is that I want to leave it pretty original.

However, I've found the culprit!!!!

I ended up ordering an original Motorcraft regulator: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Over the last fifteen years I've replaced the voltage regulator at least a dozen times in hopes of resolving this problem, and every time ended in FAILURE!!!

Amazon has the original Ford Motorcraft part and IT WORKS!!!! YAY!!!

Do not buy any aftermarket parts is the huge lesson.

[serehill]

Yeah those system really have a Vacuum to them.


Good luck.