(ET) Drat, E15 card 1 down

[Christopher Zach <cz alembic crystel com>]

E15 died this weekend, annoying. It was basically stuck, didn't respond, 
PTO switch worked, nothing else.

Towed it to the back and took a look this evening. Normally the Card 1 
on an E15 will supply power to pin 5 when the throttle is in run mode, 
and will supply power to pin 6 when it is not. The output of these then 
gate power to pin 4, which is the run contactor.

Checked switches, pin 6 gets power when the key is in, brake off, seat 
closed, throttle off. Pin 5 gets power when throttle advanced to on. 
Bypassing 5 to 4 starts the tractor in speed 1, speeds 2,3 do not come 
on, speeds 4,5,6 speed up the motor (probably with the 1a/2a contactors 
still off).

Card is out, it's probably in the pin 6 don't start the tractor till 
running circuit. Any idea which component fails first before I start 
checking?

Also why would bypassing 5-4 not get everything working? Is Q104 key to 
both the delay before speed 2 and getting the SCR going? Or is it 
something simple like C102 is dead?

Thanks!
C