It hath been written:
>>  on all vanagons the alternator does not
>>charge till the van is reved a bit, then the LED
>>alt/battery light goes out when the alt startes
>>charging the battery.

As long as it goes out and stays out after a brief rev
I wouldn't worry about it.

>This is normal. Just start the engine, rev to activate the charging, drive
>on. An old batt dash bulb can cause a higher rev needed to activate, so a
>new bulb can improve the situation,

Agreed with the fairly normal part, but nahh, ain't no bulb there. It's an LED.
The LED has a resistor in series to limit the LED current, and there is
also another resistor in parallel with the LED and its current limit resistor.
Excitation current for the alternator flows through this LED and the parallel
resistor to the D+ terminal on the alternator. It's quite possible that the
parallel resistor is burned out or damaged, resulting in insufficient
excitation
current.
Schematics in Bentley (for '86, but other years appear similar)
Alternator on 97.70. Follow wire track 61 from the D+ terminal to K2 (the LED
circuit) on page 97.74

But again if the light always goes out and stays out when revved, don't
worry...

Steve
EJ22 -> '86 Westy "Escape Pod"