When pump pressure drops to approximately 1379
kPa (200 psi), the switch circuit will re-close and
engine idle speed will return to its previous setting.
SENSOR RETURN—PCM INPUT
OPERATION
The Sensor Return circuits are internal to the Pow-
ertrain Control Module (PCM).
Sensor Return provides a low–noise ground refer-
ence for all engine control system sensors. Refer to
Power Grounds for more information.
THROTTLE POSITION SENSOR (TPS)—PCM
INPUT
DESCRIPTION
The 3–wire Throttle Position Sensor (TPS) is
mounted on the throttle body and is connected to the
throttle blade.
OPERATION
The TPS is a 3–wire variable resistor that provides
the Powertrain Control Module (PCM) with an input
signal (voltage) that represents the throttle blade
position of the throttle body. The sensor is connected
to the throttle blade shaft. As the position of the
throttle blade changes, the resistance (output volt-
age) of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from.26
volts at minimum throttle opening (idle), to 4.49 volts
at wide open throttle. Along with inputs from other
sensors, the PCM uses the TPS input to determine
current engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
The PCM needs to identify the actions and position
of the throttle blade at all times. This information is
needed to assist in performing the following calcula-
tions:
•
Ignition timing advance
•
Fuel injection pulse-width
•
Idle (learned value or minimum TPS)
•
Off-idle (0.06 volt)
•
Wide Open Throttle (WOT) open loop (2.608
volts above learned idle voltage)
•
Deceleration fuel lean out
•
Fuel cutoff during cranking at WOT (2.608 volts
above learned idle voltage)
•
A/C WOT cutoff (certain automatic transmis-
sions only)
VEHICLE SPEED AND DISTANCE SENSOR—
PCM INPUT
DESCRIPTION
The 3–wire Vehicle Speed Sensor (VSS) is located
on the speedometer pinion gear adapter. If equipped
with 4WD, this adapter is located on the extension
housing
of
the
transfer
case
(drivers
side).
If
equipped with 2WD, this adapter is located on the
left side of the transmission extension housing.
OPERATION
The VSS is a 3–circuit (3–wire), magnetic, hall-ef-
fect sensor.
The 3 circuits are:
•
A 5–volt power supply from the Powertrain Con-
trol Module (PCM).
•
A ground is provided for the sensor though a
low-noise sensor return circuit in the PCM.
•
An input to the PCM is used to determine vehi-
cle speed and distance traveled.
The speed sensor generates 8 pulses per sensor
revolution. These signals, in conjunction with a
closed throttle signal from the throttle position sen-
sor, indicate a closed throttle deceleration to the
PCM. When the vehicle is stopped at idle, a closed
throttle signal is received by the PCM (but a speed
sensor signal is not received).
Under deceleration conditions, the PCM adjusts
the Idle Air Control (IAC) motor to maintain a
desired MAP value. Under idle conditions, the PCM
adjusts the IAC motor to maintain a desired engine
speed.
AUTO SHUTDOWN (ASD) RELAY—PCM
OUTPUT
DESCRIPTION
The 5–pin, 12–volt, Automatic Shutdown (ASD)
relay is located in the Power Distribution Center
(PDC). Refer to label on PDC cover for relay location.
OPERATION
The ASD relay supplies battery voltage (12+ volts)
to the fuel injectors and ignition coil(s). With certain
emissions packages it also supplies 12–volts to the
oxygen sensor heating elements.
The ground circuit for the coil within the ASD
relay is controlled by the Powertrain Control Module
(PCM). The PCM operates the ASD relay by switch-
ing its ground circuit on and off.
The ASD relay will be shut–down, meaning the
12–volt power supply to the ASD relay will be de-ac-
tivated by the PCM if:
14 - 34
FUEL SYSTEM
XJ
DESCRIPTION AND OPERATION (Continued)
Summary of Contents for 200 Cherokee
Page 5: ...FASTENER IDENTIFICATION 4 INTRODUCTION XJ DESCRIPTION AND OPERATION Continued ...
Page 6: ...FASTENER STRENGTH XJ INTRODUCTION 5 DESCRIPTION AND OPERATION Continued ...
Page 8: ...METRIC CONVERSION CHART XJ INTRODUCTION 7 DESCRIPTION AND OPERATION Continued ...
Page 9: ...TORQUE SPECIFICATIONS 8 INTRODUCTION XJ DESCRIPTION AND OPERATION Continued ...
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Page 107: ...Fig 105 Gear Tooth Contact Patterns 3 60 TUBE 181 AND 186 FBI AXLE XJ ADJUSTMENTS Continued ...
Page 111: ...Installer D 144 Installer W 262 3 64 TUBE 181 AND 186 FBI AXLE XJ SPECIAL TOOLS Continued ...
Page 145: ...Fig 79 Gear Tooth Contact Patterns 3 98 194 RBI AXLE XJ ADJUSTMENTS Continued ...
Page 177: ...Fig 59 Gear Tooth Contact Patterns 3 130 8 1 4 REAR AXLE XJ ADJUSTMENTS Continued ...
Page 230: ...Fig 8 Clutch Components And Inspection XJ CLUTCH 6 5 DIAGNOSIS AND TESTING Continued ...
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Page 484: ...SPECIAL TOOLS HEADLAMP ALIGNMENT Headlamp Aiming Kit C 4466 A XJ LAMPS 8L 9 ...
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Page 1072: ...Fig 16 2 5L Engine XJ 8W 90 CONNECTOR LOCATIONS 8W 90 25 DESCRIPTION AND OPERATION Continued ...
Page 1073: ...Fig 17 4 0L Engine 8W 90 26 8W 90 CONNECTOR LOCATIONS XJ DESCRIPTION AND OPERATION Continued ...
Page 1074: ...Fig 18 4 0L Engine XJ 8W 90 CONNECTOR LOCATIONS 8W 90 27 DESCRIPTION AND OPERATION Continued ...
Page 1087: ...Fig 31 Liftgate 8W 90 40 8W 90 CONNECTOR LOCATIONS XJ DESCRIPTION AND OPERATION Continued ...
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Page 1331: ...Fig 6 Frame Dimensions 13 8 FRAME AND BUMPERS XJ SPECIFICATIONS Continued ...
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Page 1912: ...Fig 3 Hood Components XJ BODY 23 25 REMOVAL AND INSTALLATION Continued ...
Page 1955: ...WELD LOCATIONS UPPER COWL 23 68 BODY XJ SPECIFICATIONS Continued ...
Page 1956: ...UPPER COWL XJ BODY 23 69 SPECIFICATIONS Continued ...
Page 1957: ...COWL 23 70 BODY XJ SPECIFICATIONS Continued ...
Page 1958: ...A PILLAR XJ BODY 23 71 SPECIFICATIONS Continued ...
Page 1959: ...A PILLAR 23 72 BODY XJ SPECIFICATIONS Continued ...
Page 1960: ...A PILLAR XJ BODY 23 73 SPECIFICATIONS Continued ...
Page 1961: ...A PILLAR 23 74 BODY XJ SPECIFICATIONS Continued ...
Page 1962: ...B PILLAR XJ BODY 23 75 SPECIFICATIONS Continued ...
Page 1963: ...D PILLAR 23 76 BODY XJ SPECIFICATIONS Continued ...
Page 1964: ...FUEL FILLER OPENING XJ BODY 23 77 SPECIFICATIONS Continued ...
Page 1965: ...CARGO AREA FLOOR PAN 23 78 BODY XJ SPECIFICATIONS Continued ...
Page 1966: ...ROOF AND D PILLAR XJ BODY 23 79 SPECIFICATIONS Continued ...
Page 1967: ...LIFTGATE OPENING 23 80 BODY XJ SPECIFICATIONS Continued ...
Page 1968: ...ROOF XJ BODY 23 81 SPECIFICATIONS Continued ...
Page 1969: ...ROOF 23 82 BODY XJ SPECIFICATIONS Continued ...
Page 1970: ...FRAME RAIL XJ BODY 23 83 SPECIFICATIONS Continued ...
Page 1971: ...FRAME RAIL 23 84 BODY XJ SPECIFICATIONS Continued ...
Page 1972: ...FRAME RAIL XJ BODY 23 85 SPECIFICATIONS Continued ...
Page 1973: ...FRAME RAIL 23 86 BODY XJ SPECIFICATIONS Continued ...
Page 1974: ...REINFORCEMENT XJ BODY 23 87 SPECIFICATIONS Continued ...
Page 1975: ...FRONT INNER FENDER 23 88 BODY XJ SPECIFICATIONS Continued ...
Page 1976: ...FRONT INNER FENDER AND RADIATOR CLOSURE PANEL XJ BODY 23 89 SPECIFICATIONS Continued ...
Page 1977: ...REINFORCEMENT 23 90 BODY XJ SPECIFICATIONS Continued ...
Page 1978: ...FRONT FENDER XJ BODY 23 91 SPECIFICATIONS Continued ...
Page 1979: ...BODY SIDE 23 92 BODY XJ SPECIFICATIONS Continued ...
Page 1980: ...REAR WHEELHOUSE XJ BODY 23 93 SPECIFICATIONS Continued ...
Page 1981: ...REAR INNER WHEELHOUSE 23 94 BODY XJ SPECIFICATIONS Continued ...
Page 1982: ...BODY SIDE XJ BODY 23 95 SPECIFICATIONS Continued ...
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Page 1999: ...BODY SEALING LOCATIONS APPLICATION METHODS 23 112 BODY XJ SPECIFICATIONS Continued ...
Page 2000: ...COWL AND DASH PANEL XJ BODY 23 113 SPECIFICATIONS Continued ...
Page 2001: ...DASH PANEL AND FLOOR PAN 23 114 BODY XJ SPECIFICATIONS Continued ...
Page 2002: ...FLOOR PAN XJ BODY 23 115 SPECIFICATIONS Continued ...
Page 2003: ...REAR INNER WHEELHOUSE 23 116 BODY XJ SPECIFICATIONS Continued ...
Page 2004: ...FRONT INNER WHEELHOUSE XJ BODY 23 117 SPECIFICATIONS Continued ...
Page 2005: ...BODY SIDE 23 118 BODY XJ SPECIFICATIONS Continued ...
Page 2006: ...BODY SIDE XJ BODY 23 119 SPECIFICATIONS Continued ...
Page 2007: ...BODY SIDE 23 120 BODY XJ SPECIFICATIONS Continued ...
Page 2008: ...ROOF PANEL XJ BODY 23 121 SPECIFICATIONS Continued ...
Page 2009: ...FUEL FILLER HOUSING 23 122 BODY XJ SPECIFICATIONS Continued ...
Page 2010: ...LIFTGATE OPENING XJ BODY 23 123 SPECIFICATIONS Continued ...
Page 2011: ...STRUCTURAL ADHESIVE LOCATIONS LEFT QUARTER PANEL 23 124 BODY XJ SPECIFICATIONS Continued ...
Page 2012: ...REAR WHEELHOUSE XJ BODY 23 125 SPECIFICATIONS Continued ...
Page 2013: ...ROOF BOWS 23 126 BODY XJ SPECIFICATIONS Continued ...
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