1994 JEEP WRANGLER warning light

REMOVALÐYJ MODELS
WARNING: EXTINGUISH ALL TOBACCO SMOKING
PRODUCTS BEFORE SERVICING THE FUEL SYS-
TEM. KEEP OPEN FLAME AWAY FROM FUEL SYS-
TEM COMPONENTS.
(1) Disconnect negative battery cable.
(2) Remove the fuel filler cap. Using an approved por-
table gasoline siphon/storage tank, drain fuel tank.
(3) Raise and support vehicle.
(4) Using a small straight blade screwdriver, pull
back the stems of the push clips that secure the fuel
filler neck shroud (located at bottom of left rear
wheel well) in place (Fig. 4). This unlocks the push
clip allowing them to be removed by pulling assem-
bly out of shroud. Remove shroud.
(5) Disconnect fuel fill hose and fill vent hose from
filler neck (Fig. 5).
WARNING: WRAP SHOP TOWELS AROUND FUEL
HOSES TO ABSORB ANY FUEL SPILLAGE DURING
FUEL TANK REMOVAL.(6) Disconnect fuel tank vent hose from vent tube.
Disconnect fuel supply and return hoses from tubes
(Fig. 6).
The fuel tank and skid plate are removed as an as-
sembly.
(7) Centrally position a transmission jack under
skid plate/fuel tank assembly.
(8) Remove skid plate/fuel tank assembly mount-
ing nuts (Fig. 7).Do not loosen tank strap nuts.
(9) Lower the skid plate/fuel tank assembly
slightly and disconnect the gauge sender wire con-
nector.
(10) Lower the fuel tank on transmission jack.
(11) Remove tank strap nuts to remove tank from
skid plate.
Fig. 4 Fuel Filler Neck ShroudÐYJ Models
Fig. 5 Filler Neck HosesÐYJ Models
Fig. 6 Fuel Tank HosesÐYJ Models
Fig. 7 Fuel TankÐRemove/InstallÐYJ Models
14 - 14 FUEL SYSTEMJ

ing the IAC motor pintle in and out of the air control
passage. The IAC motor is positioned when the igni-
tion key is turned to the On position.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
IGNITION COILÐPCM OUTPUT
System voltage is supplied to the ignition coil pos-
itive terminal. The powertrain control module (PCM)
operates the ignition coil.Base (initial) ignition
timing is not adjustable.The PCM adjusts ignition
timing to meet changing engine operating conditions.
The ignition coil is located near the ignition distrib-
utor (Fig. 22).
Refer to Group 8D, Ignition System for additional
information.
MALFUNCTION INDICATOR LAMPÐPCM OUTPUT
The Malfunction Indicator Lamp (formerly referred
to as the Check Engine Lamp) illuminates on the in-
strument panel each time the ignition key is turned
on. It will stay on for three seconds as a bulb test.
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. Refer
to On-Board Diagnostics in the General Diagnosis
section of this group for more information.
RADIATOR FAN RELAYÐPCM OUTPUT
XJ MODELS ONLY
The electric radiator cooling fan used in XJ models
(equipped with 4.0L engine, heavy duty cooling
and/or air conditioning) is controlled by the power-
train control module (PCM) through radiator fan re-
lay. The relay is energized when coolant temperature
is above 103ÉC (217ÉF). It will then de-energize when
coolant temperature drops to 98ÉC (208ÉF). Refer to
Group 7, Cooling Systems for more information.
The relay is located in the power distribution cen-
ter (PDC) (Fig. 23).
The electric radiator cooling fan is not used on YJ
models.
SCI TRANSMITÐPCM OUTPUT
SCI Transmit is the serial data communication
transmit circuit for the DRB scan tool. The power-
train control module (PCM) transmits data to the
DRB through the SCI Transmit circuit.
SHIFT INDICATORÐPCM OUTPUT
Vehicles equipped with manual transmissions have
an Up-Shift indicator 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 up-shift light will remain off until vehi-
cle stops accelerating and is brought back to range of
up-shift light operation. This will also happen if ve-
hicle 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 en-
gine speed and load.
Fig. 23 PDCÐXJ Models
Fig. 22 Ignition CoilÐTypical
14 - 26 FUEL SYSTEMJ

REMOVALÐYJ MODELS
WARNING: EXTINGUISH ALL TOBACCO SMOKING
PRODUCTS BEFORE SERVICING THE FUEL SYS-
TEM. KEEP OPEN FLAME AWAY FROM FUEL SYS-
TEM COMPONENTS.
(1) Disconnect negative battery cable.
(2) Remove the fuel filler cap. Using an approved por-
table gasoline siphon/storage tank, drain fuel tank.
(3) Raise and support vehicle.
(4) Using a small straight blade screwdriver, pull
back the stems of the push clips that secure the fuel
filler neck shroud (located at bottom of left rear
wheel well) in place (Fig. 4). This unlocks the push
clip allowing them to be removed by pulling assem-
bly out of shroud. Remove shroud.
(5) Disconnect fuel fill hose and fill vent hose from
filler neck (Fig. 5).
WARNING: WRAP SHOP TOWELS AROUND FUEL
HOSES TO ABSORB ANY FUEL SPILLAGE DURING
FUEL TANK REMOVAL.(6) Disconnect fuel tank vent hose from vent tube.
Disconnect fuel supply and return hoses from tubes
(Fig. 6).
The fuel tank and skid plate are removed as an as-
sembly.
(7) Centrally position a transmission jack under
skid plate/fuel tank assembly.
(8) Remove skid plate/fuel tank assembly mount-
ing nuts (Fig. 7).Do not loosen tank strap nuts.
(9) Lower the skid plate/fuel tank assembly
slightly and disconnect the gauge sender wire con-
nector.
(10) Lower the fuel tank on transmission jack.
(11) Remove tank strap nuts to remove tank from
skid plate.
Fig. 4 Fuel Filler Neck ShroudÐYJ Models
Fig. 5 Filler Neck HosesÐYJ Models
Fig. 6 Fuel Tank HosesÐYJ Models
Fig. 7 Fuel TankÐRemove/InstallÐYJ Models
14 - 14 FUEL SYSTEMJ

ing the IAC motor pintle in and out of the air control
passage. The IAC motor is positioned when the igni-
tion key is turned to the On position.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
IGNITION COILÐPCM OUTPUT
System voltage is supplied to the ignition coil pos-
itive terminal. The powertrain control module (PCM)
operates the ignition coil.Base (initial) ignition
timing is not adjustable.The PCM adjusts ignition
timing to meet changing engine operating conditions.
The ignition coil is located near the ignition distrib-
utor (Fig. 22).
Refer to Group 8D, Ignition System for additional
information.
MALFUNCTION INDICATOR LAMPÐPCM OUTPUT
The Malfunction Indicator Lamp (formerly referred
to as the Check Engine Lamp) illuminates on the in-
strument panel each time the ignition key is turned
on. It will stay on for three seconds as a bulb test.
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. Refer
to On-Board Diagnostics in the General Diagnosis
section of this group for more information.
RADIATOR FAN RELAYÐPCM OUTPUT
XJ MODELS ONLY
The electric radiator cooling fan used in XJ models
(equipped with 4.0L engine, heavy duty cooling
and/or air conditioning) is controlled by the power-
train control module (PCM) through radiator fan re-
lay. The relay is energized when coolant temperature
is above 103ÉC (217ÉF). It will then de-energize when
coolant temperature drops to 98ÉC (208ÉF). Refer to
Group 7, Cooling Systems for more information.
The relay is located in the power distribution cen-
ter (PDC) (Fig. 23).
The electric radiator cooling fan is not used on YJ
models.
SCI TRANSMITÐPCM OUTPUT
SCI Transmit is the serial data communication
transmit circuit for the DRB scan tool. The power-
train control module (PCM) transmits data to the
DRB through the SCI Transmit circuit.
SHIFT INDICATORÐPCM OUTPUT
Vehicles equipped with manual transmissions have
an Up-Shift indicator 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 up-shift light will remain off until vehi-
cle stops accelerating and is brought back to range of
up-shift light operation. This will also happen if ve-
hicle 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 en-
gine speed and load.
Fig. 23 PDCÐXJ Models
Fig. 22 Ignition CoilÐTypical
14 - 26 FUEL SYSTEMJ

Wiring Diagram Name Sheet Number
A/C Compressor Clutch........................45
A/C Compressor Clutch Relay....................45
A/C Heater Blower Motor.......................46
A/C Low Pressure Switch.......................45
A/C Mode Selector Switch.......................46
A/C System.............................45, 46
A/C Thermostat..............................45
Antenna Mast...............................47
Ashtray Illumination Lamp.......................26
Automatic Shut Down Relay......................9
Back-up Lamp Switch.........................16
Battery....................................6
Blower Motor............................44, 46
Blower Resistor...........................44, 46
Blower Switch............................44, 46
Body Ground...............................59
Brake Warning Switch.........................42
Camshaft Position Sensor.......................12
Cargo Lamp................................30
Charging System.............................5
Generator.................................5
Check Engine Indicator Lamp..................39, 40
Chime Module..............................43
Chime Module Connector.......................71
Cigar Lighter...............................58
Circuit Breakers
Windshield Wiper Circuit Breaker...............2,33
Connectors
Chime Module Connector......................71
Dash to Instrument Panel Connector A.............64
Dash to Instrument Panel Connector B.............65
Dash to Instrument Panel Connector C.............66
Data Link Connector.........................10
Instrument Cluster Connector 16 Way...........37, 69
Main Body Connector 1.......................70
Power Mirror Connector......................61
Powertrain Control Module Connector..............73
Steering Column Connector 11 Way...............67
Telltale Connector........................38, 68
Transmission Control Module Connector............72
Transmission Data Link Connector................17
Coolant Temperature Switch......................16
Crankshaft Position Sensor......................12
Dash to Instrument Panel Connector A..............64
Dash to Instrument Panel Connector B..............65
Dash to Instrument Panel Connector C..............66
Data Link Connector..........................10
Distributor Ignition Coil........................10
Dome Lamp................................31
Dome and Courtesy Lamps.................29, 30, 31
Cargo Lamp..............................30
Dome Lamp..............................31