Sorin, I'm kinda tired so this might not be right, but I am pretty sure that
if you unhook the negative battery terminal when the engine is running on any
van that it will kill the motor.  Why?  Because you have just opened up the
return path in the circuit.  All of the electricity going to the motor has to
have a ground and you just unhooked it.  So no wonder it dies (normal).
The problem you were having with the "solenoid" (which is actually called a
coil) was really unrelated to your charging problem.  When coils go bad they
poop out black tar which insulates the coils inside from each other.
Eventually even tar will come out to allow the coils to touch which would
either kill your ignition or make the spark so weak that it wouldn't start.
The best way to check your charging system is with a multimeter between the
two terminals of the battery.  Check it when the van is not running.  Start
up the van and see what it is putting out then.  Should be around 13.6
volts-14 volts.  Higher or lower can mean problems.
Hope this helps you.

Ken Wilford
http://www.vanagain.com
John 3:16
Office (856)-765-1583
Shop (856)-327-0027
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