Prowler V6-3.5L VIN G (1999)
Automatic Shut Down (ASD) Relay: Description and Operation
AUTOMATIC SHUTDOWN (ASD) AND FUEL PUMP RELAYS
The PCM operates the ASD relay and fuel pump relay through one ground path. The PCM operates them by switching on and off the ground path
for the solenoid side of the relays. Both relays turn on and off at the same time.
The ASD relay connects battery voltage to the fuel injectors and ignition coil. The fuel pump relay connects battery voltage to the fuel pump.
The PCM turns the ground path off when the ignition switch is in the Off position. Both relays are off. When the ignition switch is in the On or
Crank position, the PCM monitors the crankshaft position sensor and camshaft position sensor signals to determine engine speed and ignition
timing (coil dwell). If the PCM does not receive a crankshaft position sensor signal and camshaft position sensor signal when the ignition switch is
in the Run position, it de-energizes both relays. When the relays de-energize, battery voltage is not supplied to the fuel injectors, ignition coil and
fuel pump.
Power Distribution Center
The ASD relay and fuel pump relay are located in the Power Distribution Center (PDC) near the battery. A decal on the underside of the PDC
cover shows the locations of each relay and fuse contained in the PDC.
AUTOMATIC SHUTDOWN (ASD) SENSE-PCM INPUT
The ASD sense circuit informs the PCM when the ASD relay energizes. A 12 volt signal at this input indicates to the PCM that the ASD has been
activated. This input is used only to sense that the ASD relay is energized.
When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils and the heating element in each oxygen sensor. If the
PCM does not receive 12 volts from this input after grounding the ASD relay, it sets a Diagnostic Trouble Code (DTC).
