re. rad fan wont stop

[ben swann]

One likely possibility is the switch located in the radiator.  Verify
by pulling the connector.  Don't get into troubleshooting the more
complex until you rule this out.  BTDT!

Ben

[Guys,
I have an '87 5K turbo and I can't get the rad fan to NOT run all the
time.  As soon as I turn on the key, the high speed fan starts.  I
thought that the switch on the rad was bad, so I pulled the wire for
the high speed. Now the low speed runs all the time (when the key is on
only).  I suspect that it was trying to run before (low speed), but
with the high speed going, there would be no way to tell.
So I am suspecting that it is not a bad switch My dealer told me that
there are a set of 3 diodes located on the frame rail that also
controls the fan.  Does this sound right?
If so, he said that he couldn't remember if they were on the right or
left frame rail, but he thought that it was the left.  I can't find
anything which resembles a bank of diodes, but I did find 2 wires which
have been spliced together and covered with heat shrink.  The wires come
from under the bracket which holds the turbo cooling booster pump.  One
is light in color (grey maybe), and the other is dark (black or
brown???)
Could these be the wires that are to have the diodes?
Like always, your help is appreciated
Later
Brian]