this PCM output. Refer to Group 25, Emission Con-
trol System for additional information.
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMP—PCM OUTPUT
The malfunction indicator lamp illuminates each
time the ignition key is turned on. It will stay on for
approximately three seconds as a bulb test. The lamp
is displayed on the instrument panel as the CHECK
ENGINE lamp.
If the powertrain control module (PCM) receives an
incorrect signal, or no signal from certain sensors or
emission related systems, the lamp is turned on. This
is a warning that the PCM has recorded a system or
sensor malfunction. In some cases, when a problem is
declared, the PCM will go into a limp-in mode. This
is an attempt to keep the system operating. It signals
an immediate need for service.
The lamp can also be used to display a Diagnostic
Trouble
Code
(DTC).
Cycle
the
ignition switch
On-Off-On-Off-On within three seconds and any
codes stored in the PCM memory will be displayed.
This is done in a series of flashes representing digits.
The lamp is also used to detect certain engine mis-
fires. Refer to Group 25, Emission Control System for
more information.
OVERDRIVE LAMP—PCM OUTPUT
This circuit controls a signal for the operation of
the instrument panel mounted push-button overdrive
lamp switch. When the lamp is illuminated, the over-
drive is disengaged.
SPEED CONTROL SOLENOIDS—PCM OUTPUT
Speed control operation is regulated by the power-
train control module (PCM). The PCM controls the
vacuum to the throttle actuator through the speed
control vacuum and vent solenoids. Refer to Group
8H for Speed Control Information.
TACHOMETER—PCM OUTPUT
The powertrain control module (PCM) supplies
engine rpm values to the instrument cluster tachom-
eter. Refer to Group 8E for tachometer information.
THREE-FOUR SHIFT SOLENOID—PCM OUTPUT
This output is used to control the transmission
three-four shift solenoid. It is used on 4–speed elec-
tronically controlled automatic transmissions only.
TORQUE CONVERTOR CLUTCH (TCC) SOLENOID—
PCM OUTPUT
This circuit controls operation of the transmission
mounted torque convertor clutch (TCC) solenoid used
for torque convertor engagement.
The powertrain control module (PCM) will deter-
mine when to engage and disengage the solenoid by
monitoring vehicle miles per hour (mph) versus the
output voltage of the throttle position sensor. Also
needed are various inputs from:
•
Transmission temperature sensor
•
Output shaft speed sensor
•
Module timer
•
Engine rpm
•
MAP sensor
•
Brake switch
MANUAL TRANSMISSION
If equipped with a manual transmission, this PCM
output will control operation of the shift indicator
lamp (if equipped with lamp). The lamp is controlled
by the powertrain control module (PCM). The lamp
illuminates on the instrument panel to indicate when
the driver should shift to the next highest gear for
best fuel economy. The PCM will turn the lamp OFF
after 3 to 5 seconds if the shift of gears is not per-
formed. The lamp will remain off until vehicle stops
accelerating and is brought back to range of up-shift
lamp operation. This will also happen if vehicle is
shifted into fifth gear.
The indicator lamp is normally illuminated when
the ignition switch is turned on and it is turned off
when the engine is started up. With the engine run-
ning, the lamp is turned ON/OFF depending upon
engine speed and load.
TRANSMISSION RELAY—PCM OUTPUT
The output to this relay provides battery voltage to
the overdrive (OD), torque converter clutch (TCC)
and governor pressure solenoids. Once battery volt-
age is applied to the solenoids, they are individually
activated by the PCM through OD, TCC and gover-
nor pressure outputs. The relay is located in the
Power Distribution Center (PDC). Refer to label on
PDC cover for relay location.
GOVERNOR PRESSURE SOLENOID—PCM OUTPUT
This solenoid regulates the transmission fluid line
pressure to produce the governor pressure necessary
for transmission shift control. It is used on 4–speed
electronic transmissions only.
THROTTLE BODY—5.2L/5.9L ENGINES
Filtered air from the air cleaner enters the intake
manifold through the throttle body (Fig. 20). Fuel
does not enter the intake manifold through the throt-
tle body. Fuel is sprayed into the manifold by the fuel
injectors. The throttle body is mounted on the intake
manifold. It contains an air control passage (Fig. 21)
controlled by an idle air control (IAC) motor. The air
control passage is used to supply air for idle condi-
ZG
FUEL SYSTEM
14 - 41
DESCRIPTION AND OPERATION (Continued)
Summary of Contents for 1997 Grand Cherokee
Page 6: ...FASTENER IDENTIFICATION 4 INTRODUCTION ZG GENERAL INFORMATION Continued ...
Page 9: ...METRIC CONVERSION ZG INTRODUCTION 7 GENERAL INFORMATION Continued ...
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Page 282: ...COOLING SYSTEM DIAGNOSIS DIESEL ENGINE 7 8 COOLING SYSTEM ZG DIAGNOSIS AND TESTING Continued ...
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Page 285: ...ZG COOLING SYSTEM 7 11 DIAGNOSIS AND TESTING Continued ...
Page 286: ...7 12 COOLING SYSTEM ZG DIAGNOSIS AND TESTING Continued ...
Page 290: ...SERPENTINE DRIVE BELT DIAGNOSIS 7 16 COOLING SYSTEM ZG DIAGNOSIS AND TESTING Continued ...
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Page 423: ...VIC Initial Set Up ZG INSTRUMENT PANEL SYSTEMS 8E 21 SERVICE PROCEDURES Continued ...
Page 424: ...VIC Reset 8E 22 INSTRUMENT PANEL SYSTEMS ZG SERVICE PROCEDURES Continued ...
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Page 1655: ...Fig 3 Oil Lubrication System ZG 5 2L ENGINE 9 57 DESCRIPTION AND OPERATION Continued ...
Page 1684: ...TORQUE 9 86 5 2L ENGINE ZG SPECIFICATIONS Continued ...
Page 1689: ...Fig 3 Oil Lubrication System ZG 5 9L ENGINE 9 91 DESCRIPTION AND OPERATION Continued ...
Page 1723: ...DIAGNOSIS AND TESTING SERVICE DIAGNOSIS DIESEL PERFORMANCE ZG ENGINE 9 3 ...
Page 1724: ...9 4 ENGINE ZG DIAGNOSIS AND TESTING Continued ...
Page 1725: ...ZG ENGINE 9 5 DIAGNOSIS AND TESTING Continued ...
Page 1726: ...9 6 ENGINE ZG DIAGNOSIS AND TESTING Continued ...
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Page 1729: ...SERVICE DIAGNOSIS DIESEL MECHANICAL ZG ENGINE 9 9 DIAGNOSIS AND TESTING Continued ...
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Page 1762: ...SPECIFICATIONS ENGINE SPECIFICATIONS 9 42 ENGINE ZG ...
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Page 2122: ...DIAGNOSIS AND TESTING NV231 DIAGNOSIS 21 8 TRANSMISSION AND TRANSFER CASE ZG ...