Voltmeter reading low, alternator and batts good

Slipping belts and or a worn out alt pulley can do the same thing. Hope you have that solved. Now tell us about the green car.

 

Ditto,

I'm not sure why everyone gets so hooked on checking voltage for alternator output. You can have 14V all day long with only 5 amps of current. Amp clamps are the only way to test starters and alternators for potential issues. Voltage dropping cables is great, but that doesn't check the component under working conditions.

 

Sounds like you could be getting a brand of cheap alternators. There is an unbelievable amount of import crap getting into the parts stores now days. Probably the slip ring brushes depending on which technology this alternator uses. On the new cheap alternators, the brushes are often caged in plastic guides. They overheat in normal service, begin to soften and deform, and soon the brushes get stuck and can no longer make good contact. The brush springs also loose spring force when overheated. Just a little loss of contact pressure causes even more heat to be generated. Sometimes the regulator is crap and just cannot sustain full output drive without damage to the semiconductors. Cheap junk.

I always overhaul my own alternators. That way I can inspect and judge each part that goes into that alternator.

 

Did you ever figure it out ? I’m having the same problem on my 99 w900 3406 e model

 

Hey can someone please help me with voltage gauge and fuel gauge on my classic.
1. Fuel gauge works fine if my fan is off but as soon as i turn my fan on fuel gauge starts falling off.
2. Voltage gauge- it keeps on showing fluctuations between 12.5 to 13.9 or maybe hits 14 or above once in a while.
I’m assuming maybe a short circuit or something somewhere. I just needs someone to point me in right direction or where to start from. (Detroit 2008 fully deleted) alternator wiring cleaned all the way. And motor has new sensor Harness and injector harness.