need help in electrical measurements(ISV)

[Konstantin Bogach]

Hi listers.

Lately 200 '89 MC1started to  idle rough.  I tried to check IS system
using SJM's instructions.  What I can not understand is why ISV buzzes
only if I use mA range on DMM?  If I use A or microA it does not buzz
and DMM shows nothing (.002 as with open circuit).
Another question:
When I use mA range ISV buzzes and DMM shows 0L. which I interpret as
infinity.
SJM covers 0 reading but does not cover infinity reading.  I am pretty
weak in electronics.  Can someone help to interpret this reading?  ISV
control unit outputs high current beyond mA range can show?  Why can't I
measure it in A range?
Temp sensor is fine.

Thanks a lot.

Konstantin Bogach.