RE: After-run

["Gary Barry" <Gary.Barry@trw.com>]

I own an 86 5000CST and after a few weeks of being stuck with a dead
battery, I finally solved the problem.  Yes it was related to the after
run system.  The secondary cooling pump froze and took out the pump
driver transistor in the control module in the auxiliary relay panel
(over the drivers knees in the dash).  Since the pump was not running to
circulate coolant and the timing function in the control module quit
working, the fan ran until the thermo switch (mounted with the
multifunction switch near the thermostat) stopped it after the engine
cooled itself.  The trouble comes when you drive consecutive short
distances and the fan runs for a long period of time each time you
stop.  The battery doesn't have sufficient time to charge on each short
hop. Normally with the secondary pump running along with the fan, the
engine will cool in a few minutes and the thermo switch will shut
everything down.  A working control module prevents long runs in the
event the thermo switch doesn't open first.  The switch on the radiator
controls the second and third speeds of the fan when the engine is
operating and has no afterun function.  I was able to replace the
transistor in the module and the pump which cured the problem.  Any
arrows?
Gary Barry