Jeep 1996 Grand Cherokee Service Manual - page 1081
AUTO SHUTDOWN (ASD) RELAY—PCM OUTPUT
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 12).
The ASD supplies battery voltage to the fuel pump,
fuel injector, ignition coil, generator field winding
and oxygen (O2S) sensor heating element. The
ground circuit for the coil in the ASD relay is con-
trolled by the powertrain control module (PCM). The
PCM operates the relay by switching the ground cir-
cuit on and off.
The fuel pump relay is controlled by the PCM
through same circuit that the ASD relay is con-
trolled.
DATA LINK CONNECTOR—PCM INPUT AND
OUTPUT
The 16–way data link connector (diagnostic scan
tool connector) links the Diagnostic Readout Box
(DRB) scan tool or the Mopar Diagnostic System
(MDS) with the powertrain control module (PCM).
The data link connector is located under the instru-
ment panel to the left of the steering column (Fig.
13). For operation of the DRB scan tool, refer to the
appropriate Powertrain Diagnostic Procedures ser-
vice manual.
DUTY CYCLE EVAP PURGE SOLENOID VALVE-PCM
OUTPUT
Refer to Group 25, Emission Control System for
information.
FUEL INJECTORS—5.2L ENGINES—PCM OUTPUT
The fuel injectors are attached to the fuel rail (Fig.
14). 5.2L V-8 engines use eight injectors.
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a
sequential order by the powertrain control module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
During start up, battery voltage is supplied to the
injectors through the ASD relay. When the engine is
operating, voltage is supplied by the charging sys-
tem. The PCM determines injector pulse width based
on various inputs.
FUEL INJECTORS—4.0L ENGINE—PCM OUTPUT
Six individual fuel injectors are used with the 4.0L
6-cylinder engine. The injectors are attached to the
fuel rail (Fig. 15).
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector.
The injectors are energized individually in a
sequential order by the powertrain control module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
Fig. 13 Data Link Connector Location
Fig. 14 Fuel Injectors—5.2L Engines—Typical
14 - 36
FUEL SYSTEM
ZJ
DESCRIPTION AND OPERATION (Continued)