JMOR,
There is a downstream solenoid on the 3600 that feeds the
thermostart. It is hard to see in the photo, but, there is the
male spade terminal above the top 2 posts. That is what
energizes the solenoid.
On the starter solenoid, there should be 3 wires on the left
post, or top post. 1 is the batt + cable, 2nd is the main
ignition switch batt + feed that controls all electric including the
charging system, lighting, etc. The 3rd wire goes to the batt +
post on the thermostart solenoid. That solenoid is a
conventional automotive solenoid like this:
The key switch in this mystery is what concerns me. I went
through the user post history and read every post by the
Original Poster. His first trouble was about new battery cables,
which seemed to fix the situation. Then, a few months later, he
posted that he thought the key switch was bad and so he
replaced it and that is when the problems really started.
The factory diesel thermostart key switch is different from what
I am used to on my older 7000 diesel. On the 7000
thermostart, turning the key clockwise goes to -RUN- position,
then -START- position and springs back to -RUN- when you let
go of the key. Turning it clockwise, it goes to -THERMOSTART-
then -THERMOSTART_START- and releasing the key springs it
back to -THERMOSTART-. Once engine is running smooth, the
key gets turned to normal -RUN- position clockwise.
On the 3600, the key switch is different. You turn the key
clockwise to -RUN- then next position is spring loaded -THERMOSTART-
and the next position is spring loaded -START-. When you
release the key, it is supposed to spring back from -START-
to the -RUN- past the -THERMOSTART- position. I have seen
some of the new aftermarket switches and factory switches
that won't spring from -START- to -RUN-, instead they
spring from -START- back to -THERMOSTART-, which leaves
a large drain on the battery, as it is basically a dead short
through the heating coil. It sounds to me like the switch he
bought won't spring back from -THERMOSTART- to -RUN-.
If it was me, I would get the Ford factory switch and toss the
new switch he installed. That is what caused a lot of problems
along with the starter replacement after his friend ruined the
starter. I assume that when he replaced the starter, he didn't
put all 3 wires on the same post, as the new starter could be
different with the posts, compared to the old. That is why I
posted the photos of the different style starters available.