Vision V6-3.5L VIN F (1997)
Main Relay (Computer/Fuel System): Description and Operation
Fig. 57 ASD and Fuel Pump Relay Terminals
PURPOSE
Relay supplies battery voltage to fuel pump relay, fuel injectors, ignition coil, and O2 sensor heating element when energized by Powertrain
Control Module (PCM).
OPERATION
The PCM energizes Auto Shutdown (ASD) relay by supplying relay ground, when ignition switch is in START or RUN position and PCM is
receiving a reference signal from distributor.
When the ground is applied, the relay is energized, and voltage is allowed to flow to fuel pump, fuel injectors, ignition coil, generator field
winding, and O2 sensor heating element.
When PCM does not receive reference signal from ignition system, (indicating engine is not running), then the PCM interrupts relay ground circuit
and no voltage is supplied to fuel pump, fuel injectors, ignition coil, generator field winding, and O2 sensor heating element.
The PCM controls fuel pump relay and ASD relay simultaneously, through same ground circuit.
CIRCUIT OPERATION
The Automatic Shut Down (ASD) relay is located in the Power Distribution Center (PDC). Power for the coil, and contact sides of the relay is
provided by circuit A14. This circuit is HOT at all times, and is protected by a 20 Amp fuse in cavity B of the PDC.
The Powertrain Control Module (PCM) controls the ground path for the coil side of the relay on circuit K51. This circuit connects to cavity 67 of
the Powertrain Control Module (PCM) connector.
When the ASD relay is energized, the contacts internal to the relay CLOSE connecting circuits A14 and A142. The A142 circuit is spliced and
provides power to the fuel injectors, generator, and the PCM.
