Maybe a review again.
Digital Voltmeter (Harbor Freight $5)
Set it to 20 volts DC
Check battery voltage at battery posts - engine off (either battery, don't matter) Example 12.5 Volts
Now crank it up
Check the same battery posts, if the alternator is charging, there will be an improvement in the voltage, Example now it might read 14 Volts.
If there is no improvement, the alternator may be 'good', it's just not reaching the battery.
Beings that you have a Diesel, the only drain it takes is to crank it over (I'm no diesel guy, there may be little goodies that help run it, computer and such)
I can see the "no drain" when running, but when you fire up your headlights and such, you have a drain.
Are we sure the alternator is reaching the battery?
What are your test results with the voltmeter?
Not trying to be a pain, many folks never do the testing, they sling parts at it.
I'm sorta hung up on maybe a fusible link- Need your testing input!
Monday, January 16th, 2017 AT 6:32 PM