Cutlass V8-350 5.7L DSL (1984)
reach its ``Hot'' position is dependent upon how cold the engine and control module were when the system was first energized. As the pre-glow switch
reaches the ``Hot'' position, the wait lamp deactivates and the engine may now be started. The control module continues to operate, whether the engine is
started or not, since the after-glow switch has not yet reached its ``Hot'' position. Current flow continues to heat the thermal control. When the thermal
control reaches full temperature, the after-glow switch moves to ``Hot,'' opening the path to ground from the coil of the glow plug relay. This allows
current flow to bypass the coil of the reset relay. With the path to ground now open, current must flow to bypass the coil of the reset relay. With the path
to ground now open, current must flow to ground through the reset relay coil. The glow plug relay de-energizes, removing power to the glow plugs. The
reset relay now energizes, opening the contact of the relay and locking off the thermal controls. When the ignition switch is turned off, the reset relay
contact closes, and the glow plug module is ready to repeat the cycle. If the engine is above 140°F when restarted, the thermal controls will be ``Hot,''
energizing the reset relay and preventing glow plug operation.
The over-voltage protector protects the glow plugs should battery voltage rise above 14 volts. When the protector senses over 14 volts, it opens the
circuit to the glow plug relay coil and prevents current from flowing to the glow plugs. After a short time, the protector closes the circuit. If battery
voltage is still above 14 volts, it will reopen the circuit again. The protector continues to cycle in this way as long as the over-voltage condition exists
and as long as glow plug operation is needed.
