Alternator 28 Volts 60 Ampere

[Steffen777]

Hello everyone,
my name is Steffen and I live in Germany. I hope I have posted this in the right place. If not, I apologize.
I've had a problem since Saturday with my HMMWV M998.

I noticed that the positive cable on the alternator was loose. I noticed this because there was a slight smell of burnt plastic.
I thought I would clean the contact, polish the metal and tighten the cable, and the problem would be solved.
Unfortunately, that wasn't the case.
After that, my “Wait before Start” light stayed on for about 25-30 seconds and my charge indicator was in the yellow range for 25-30 seconds.
After the 25-30 seconds time, the light goes out and the charge indicator turns “green.”
Previously, it always took 5 seconds for the light to go out. The charge indicator was always in the green range.
I then measured the voltage of the batteries. Both were 12.8 volts.
I then measured the output of the alternator. Result: 13.8 volts!

Has anyone ever had this problem? Can anyone tell me how to measure the alternator, or does anyone have instructions?
It is a Sielmann S.A. Hellas - MSN 2920-00-9092483 (P/N 1092986
I have searched through all the technical manuals I have, but haven't found anything. I think I have also searched through everything on the intranet. Instructions on how to completely check/measure the alternator would be great.
I just want to rule out the possibility that a capacitor, rectifier, or the winding is broken.
And I really hope that it's not the “protective control box.”
Maybe it's “just” the regulator? I don't want to replace parts based on suspicion alone.

That's why I thought I'd write here in the forum.

I would be very grateful for any help.

 

[NDT]

This stud shown in the picture should always have +24 volts on it. The little wire is the excite wire and it will have +24 volts with the ignition on. Check for issues with the Cannon plug going into the Protective box.

 

[Mogman]

If you are seeing 13.8V at the alt output then there is an issue between the alt and the batteries it should be darn close to the battery voltage.
IE 12.8X2= 25.6V, this is the min (within reason) that you see at the alt.
There is a relay in your start box that controls the connection between the alt and the batteries (no voltage at the alt with the run switch off)
This relay is one of the common failure points in the start box, that relay also excites the alt and powers things like the W wipers and the heater fan, so check them for proper operation.

 

[Steffen777]

Thank you very much for your answers and quick help. I will check it out in the next few days. If it is due to the relay in the start box, can this relay be purchased separately? Is there an online store where it can be ordered?