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  #1  
Old 06-17-2016, 11:52 AM
Beach_Dude's Avatar
Beach_Dude Beach_Dude is offline
327 Rambler
 
Join Date: Mar 03, 2011
Location: Newport Beach
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Replacing Excitor wire with Copper & Resistor

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?
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1977 Jeep Cherokee Chief
360 w/ MC 4350
All stock but ignition and slightly modified suspection
Original paint, garaged/non-op for over 15 years

Last edited by Beach_Dude : 06-18-2016 at 01:47 PM.
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  #2  
Old 06-17-2016, 12:15 PM
JeepJeepster JeepJeepster is offline
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Location: Kentucky
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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.
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1998 Jeep ZJ 5.9
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1989 Jeep Grand Wagoneer 360
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  #3  
Old 06-17-2016, 05:44 PM
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Beach_Dude Beach_Dude is offline
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Join Date: Mar 03, 2011
Location: Newport Beach
Posts: 585
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!
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1977 Jeep Cherokee Chief
360 w/ MC 4350
All stock but ignition and slightly modified suspection
Original paint, garaged/non-op for over 15 years

Last edited by Beach_Dude : 06-18-2016 at 09:10 PM.
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  #4  
Old 06-19-2016, 01:43 PM
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tgreese tgreese is offline
 
Join Date: May 29, 2003
Location: Medford MA USA
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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.
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Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
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Last edited by tgreese : 06-19-2016 at 02:41 PM.
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  #5  
Old 06-20-2016, 03:23 PM
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serehill serehill is offline
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Join Date: Nov 22, 2009
Location: Mesquite Texas
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Dotto

Quote:
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.
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80 Cherokee
360 ci 727 with
Comp cams 270 h
NP208
Edlebrock performer intake
Holley 4180
Msd total multi spark.
4" rusty's springs
Member, FSJ Prissy Restoration Association

If you can't make it better why waste your time. No use repeating the orignal mistakes. I'm to old to push it that's why.
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  #6  
Old 06-21-2016, 11:12 AM
Beach_Dude's Avatar
Beach_Dude Beach_Dude is offline
327 Rambler
 
Join Date: Mar 03, 2011
Location: Newport Beach
Posts: 585
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.
__________________
1977 Jeep Cherokee Chief
360 w/ MC 4350
All stock but ignition and slightly modified suspection
Original paint, garaged/non-op for over 15 years

Last edited by Beach_Dude : 06-24-2016 at 11:19 AM.
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  #7  
Old 06-21-2016, 11:23 AM
serehill's Avatar
serehill serehill is offline
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Join Date: Nov 22, 2009
Location: Mesquite Texas
Posts: 8,619
Glad to see you got it

Yeah those system really have a Vacuum to them.


Good luck.
__________________

80 Cherokee
360 ci 727 with
Comp cams 270 h
NP208
Edlebrock performer intake
Holley 4180
Msd total multi spark.
4" rusty's springs
Member, FSJ Prissy Restoration Association

If you can't make it better why waste your time. No use repeating the orignal mistakes. I'm to old to push it that's why.
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