RAM 3500 Truck 4WD V10-8.0L VIN W (1997)
Automatic Shut Down (ASD) Relay: Description and Operation
DESCRIPTION
As one of its functions, the ASD relay will supply battery voltage to each of the 5 independent ignition coils. The ground circuit for the ASD relay
is controlled by the PCM. The PCM regulates ASD relay operation by switching the ground circuit on-and-off.
CIRCUIT OPERATION
Automatic Shut Down (ASD) Relay
When the ignition switch is in the START or RUN position, it connects circuit A1 from fuse 3 in the Power Distribution Center (PDC) to circuit
A21. Circuit A21 powers circuit F18 through fuse 9 in the fuse block. Circuit F18 supplies battery voltage to the coil side of the ASD relay The
Powertrain Control Module (PCM) provides the ground path for the coil side of the relay on circuit K51. Circuit K51 connects to cavity C3 of the
PCM.
When the PCM grounds the ASD relay, the relay contacts close and connect circuit A16 from fuse 4 in the PDC to circuit K125. Circuit K125
splices to supply voltage to the fuel injectors, ignition coil, and heated oxygen sensors. Circuit K125 also connects to cavity C12 of the PCM.
Fuel Shut Down Relay
When the engine starter motor relay energizes, its contacts close and connect circuit A2 from fuse 2 in the Power Distribution Center (PDC) to
circuit T40. Circuit T40 supplies battery voltage to the engine starter motor solenoid and to the coil side of the fuel shut down relay. Circuit Z12
provides ground for the coil side of the relay.
Circuit A18 from the Power Distribution Center (PDC) supplies battery voltage to the contact side of the fuel shut down relay When voltage is
present on circuit T40, the relay energizes and its contacts close to connect circuits A18 and A123. Circuit A123 supplies power to one of the two
coils in the fuel shut down solenoid.
When circuit A123 energizes, the fuel shut down solenoid raises the injection pump shut down lever to the RUN position.
When the ignition switch is released to the RUN position, it connects circuit A1 from fuse 3 in the PDC to circuit A21. Circuit A21 powers circuit
F18 through fuse 9 in the fuse block. Circuit F18 supplies battery voltage to the second coil in the fuel shut down lever. When Circuit F18
energizes, the fuel shut down solenoid holds the injection pump shut down lever in the RUN position.
Circuit Z12 provides ground for the fuel shut down solenoid.
