1980 Ford 445 diesel tractor new alternator output only 12.28

[gnc23]

Thought we were done restoring this 1980 diesel Ford 445 tractor. Having problem with new alternator output only 12.28 when idling and same volts when increase rpm. Put new wire harness D6NN14A103J from Sparex Ag Parts #S.67792, new 32amp Alternator D5NN10300ER, and new regulator Model 8RH2023 4 amp 12 volt D7NN10316B. Hooked everything up as wiring diagrams and manual says but alternator only puts out 12.28. Took alternator to a Shop and had tested, alternator is good. Did a Regulator bypass test via Service manual (disconnected field lead from F terminal on alt, connected jumper wire from R terminal to F terminal and took reading at idle and also at increased rpm) and alternator increases output to 14v+ when increase rpms with regulator bypassed. Bought another new regulator thinking I got a faulty one but same issue. So, I am pretty sure alternator is good, regulator is good, wiring harness is new, but could the wiring be wrong? I followed wiring diagram with wire harness to alternator: black is ground, blue is R regulator, red is F field, red w/ eyelet is Output. I am at a loss and need to get this tractor done. Any input is greatly appreciated. Ready to say screw it and get a 1 wire alternator. Anyone know a part# for a 1 wire alternator that will fit Ford 445 diesel tractor?

 

[Bern]

Thought we were done restoring this 1980 diesel Ford 445 tractor. Having problem with new alternator output only 12.28 when idling and same volts when increase rpm. Put new wire harness D6NN14A103J from Sparex Ag Parts #S.67792, new 32amp Alternator D5NN10300ER, and new regulator Model 8RH2023 4 amp 12 volt D7NN10316B. Hooked everything up as wiring diagrams and manual says but alternator only puts out 12.28. Took alternator to a Shop and had tested, alternator is good. Did a Regulator bypass test via Service manual (disconnected field lead from F terminal on alt, connected jumper wire from R terminal to F terminal and took reading at idle and also at increased rpm) and alternator increases output to 14v+ when increase rpms with regulator bypassed. Bought another new regulator thinking I got a faulty one but same issue. So, I am pretty sure alternator is good, regulator is good, wiring harness is new, but could the wiring be wrong? I followed wiring diagram with wire harness to alternator: black is ground, blue is R regulator, red is F field, red w/ eyelet is Output. I am at a loss and need to get this tractor done. Any input is greatly appreciated. Ready to say screw it and get a 1 wire alternator. Anyone know a part# for a 1 wire alternator that will fit Ford 445 diesel tractor?

Since you say that this is a restoration, it would be preferable in my mind to get the original system going. Based on everything you've done, it sounds like the problem is with your external excitation circuit. Hopefully the attached images will help. They are from a training booklet Ford put out for just these Motorola systems.

I'm not sure on your colors, but if the wire harness is period correct, there should be no way to get the connections wrong on the back of the alternator. With regards to the wiring harness side of things, the ground terminal should be a female bullet connector, the field wire should be a female spade, and the regulator wire should be a male spade. The largest wire is the output. By the way, 12.28 volts basically means the charging system is doing absolutely nothing.

 

[Texasmark]

Ensure that your control wire is connected to the new alternator. Without the control wire connected it won't energize. The other wire/wires are ground to the case and the high current wire(s) back to the battery. I just went through that with a OTC replacement alternator, not OEM.

 

[gnc23]

Thanks for the replies. I must apologize for using the word "Restoration", I was using it loosely. We took a very hard worked 40yr old farm tractor and brought it back to the best condition we could. It's still going to be a working farm tractor but restored to like new. As for my charging issue Bern, thanks, I am going to do the Regulator input test next. I greatly appreciate your help. TexasMark, what do u mean by the "control wire"?
I appreciate your input as well. Attached are a before and after pic of the 1980 Ford 445 we've been working on. Thanks, will let y'all know.

 

[Bern]

Thanks for the replies. I must apologize for using the word "Restoration", I was using it loosely. We took a very hard worked 40yr old farm tractor and brought it back to the best condition we could. It's still going to be a working farm tractor but restored to like new. As for my charging issue Bern, thanks, I am going to do the Regulator input test next. I greatly appreciate your help. TexasMark, what do u mean by the "control wire"?
I appreciate your input as well. Attached are a before and after pic of the 1980 Ford 445 we've been working on. Thanks, will let y'all know.

Very nice. I'd say that looks restored to me.

 

[Texasmark]

Thanks for the replies. I must apologize for using the word "Restoration", I was using it loosely. We took a very hard worked 40yr old farm tractor and brought it back to the best condition we could. It's still going to be a working farm tractor but restored to like new. As for my charging issue Bern, thanks, I am going to do the Regulator input test next. I greatly appreciate your help. TexasMark, what do u mean by the "control wire"?
I appreciate your input as well. Attached are a before and after pic of the 1980 Ford 445 we've been working on. Thanks, will let y'all know.

Bern gave you a schematic for an external regulator circuit. I am talking about an alternator with an internal rectifier/regulator. The control wire is the small wire that has 12v from the ignition switch when in the ON position and allows the alternator to function.