1988 JEEP CHEROKEE heater

SEAT HEATERS
See
HEATING ELEMENTS (DEFROSTERS, DEFOGGERS, ELECTRIC HEATERS AND SEATS) .
SECURITY ALARM SENSORS
SECURITY ALARM SENSOR INSPECTION








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Condition Code Procedure
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware threads
damaged ................ A ... Require repair or replacement
of hardware.
Attaching hardware threads
stripped (threads
missing) ............... A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector melted ........ A ........... ( 1) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.
Inoperative ............. B ........... ( 2) Require repair or
replacement. Further
inspection required.
Missing ................. C ............ Require replacement.
Resistance out of
specification .......... B .. Require repair or replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of OEM
specification.









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SIRENS

\003
EN G IN E R EM OVA L - 4 -C YL

1988 J e ep C hero ke e
1988 ENGINES
Jeep - Engine Removal - 4-Cylinder
Cherokee, Comanche, Wrangler
4-CYLINDER ENGINES
2.5L
1) Disconnect negative battery cable. Drain cooling system.
Remove air cleaner, lower radiator hose, fan shroud, and engine
compartment light from hood. Scribe hinge locations and remove hood.
Disconnect automatic transmission cooler lines at radiator (if
equipped).
2) Remove upper radiator hose, fan assembly and coolant
recovery hose. Remove radiator and A/C condenser (if equipped). Hold
fan pulley to water pump flange using 5/16" x 1/2" SAE capscrew.
Disconnect heater hoses, throttle linkages, cruise control cable (if
equipped) and Throttle valve rod.
3) Disconnect wires from starter and separate CEC system
wiring harness connector. Disconnect fuel pipe from fuel pump and fuel
return hose from fuel filter. Disconnect hoses from A/C compressor and
power steering pump (if equipped). Drain power steering pump
reservoir. Cap all fittings and hose ends.
4) Remove vacuum check valve from brake booster (if
equipped). Tag and remove all wiring and vacuum lines connected to
engine or accessories. Raise vehicle and remove starter. Disconnect
exhaust pipe from manifold.
5) Remove converter/flywheel housing cover. Remove engine
mount nuts at bracket side. On automatic transmission models, index
mark drive plate and torque converter. Remove drive plate-to-converter
bolts.
6) Remove upper and loosen lower bellhousing-to-engine bolts.
Attach lifting equipment to engine. Raise engine off front mounts,
Place support under bellhousing. Remove remaining bellhousing-to-
engine bolts. Lift engine out of engine compartment.
NOTE: Engine mount pads may be removed from engine brackets to
align engine and transmission during installation.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Clutch Housing-to-Block Bolts .................... 55 (75)
Drive Plate-to-Converter ......................... 26 (35)
Flywheel Bolts ............................... ( 1) 50 (68)
Front Support Bracket-to-Block ................... 45 (61)
Front Support Cushion-to-Crossmember ............. 33 (45)
Rear Support Bracket-to-Transmission ............. 33 (45)
Rear Support Cushion-to-Bracket .................. 30 (41)
Starter Motor-to-Block ........................... 33 (45)
( 1) - Tighten an additional 60 degrees.









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\003
EN G IN E R EM OVA L - 6 -C YL

1988 J e ep C hero ke e
1988 ENGINES
Jeep - Engine Removal - 6-Cylinder
Cherokee, Comanche, Wagoneer, Wrangler
6-CYLINDER ENGINES
4.0L
1) Scribe hinge locations, remove engine compartment light
(if equipped) and remove hood. Disconnect battery cables and remove
battery. Drain cooling system.
2) Disconnect wire connectors from alternator, ignition coil
and distributor. Disconnect oil pressure sender wire, starter wires
and fuel injector wiring harness (if equipped). Detach 2 fuel pipe
quick connect couplings at left inner fender panel. Disconnect engine
ground strap and remove air cleaner.
3) Disconnect the vacuum purge hose at fuel vapor canister
tee. Disconnect wire from idle speed actuator and oxygen sensor.
Detach throttle cable from bracket and disconnect throttle valve rod
at bellcrank. Remove upper and lower radiator hoses.
4) On automatic transmission models, disconnect the
transmission fluid cooler tubing. On all models, remove fan shroud and
radiator. Remove fan and spacer or Tempatrol fan assembly. Hold fan
pulley to water pump flange using 5/16" x 1/2" SAE capscrew while
crankshaft is rotated.
5) Disconnect cruise control cable (if equipped). Disconnect\
wires from starter motor solenoid and disconnect CEC system harness.
Remove power brake vacuum check valve from booster (if equipped).
6) Disconnect power steering hoses from steering gear (if
equipped). Drain power steering pump reservoir and plug end of hoses.
Cap all fittings on steering gear and hoses. Raise and support
vehicle. Remove starter. Remove flywheel housing access cover.
7) Remove upper and loosen lower bellhousing-to-engine bolts.
Attach lifting equipment to engine. Raise engine off front mounts.
Place support under bellhousing. Remove remaining bellhousing-to-
engine bolts. Lift engine out of engine compartment.
4.2L
1) Remove battery and drain cooling system. Remove air
cleaner and engine compartment light from hood. Scribe hinge location
and remove hood. Disconnect and plug front fuel line at pump and fuel
return line at frame.
2) Disconnect heater hoses at heater. Label and disconnect
all wiring, lines, linkage and hoses at engine. Remove vacuum switch
assembly bracket from cylinder head cover. Remove both radiator hoses
and automatic transmission oil lines (if equipped) at radiator. Remove\
radiator and shroud.
3) Remove fan and spacer. Use 5/16" x 1/2" SAE bolt to hold
fan pulley to water pump flange. Remove starter and disconnect engine
ground strap. Remove engine mount-to-bracket nuts. Disconnect exhaust
pipe at manifold.
4) Discharge A/C system (if equipped). Disconnect and plug
hose or port openings at compressor. Disconnect hoses at power
steering gear and drain reservoir. Remove power brake vacuum check
valve. Remove bracket bolt for automatic transmission filler tube (if
equipped).
5) Lift and support vehicle. On models with automatic

FUEL TANKS
GAS CAPS
GASKETS
GROMMETS (VALVE COVER)
HARMONIC DAMPERS
HEATER CONTROL VALVES
HEATER CORES
HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS
HOSE CLAMPS
HOSE CONNECTORS
HOSE COUPLERS
HOSES AND TUBES (FUEL LINES, RADIATOR, VACUUM, BY PASS,
HEATER, RECOVERY TANK AND OIL COOLERS)
HOUSINGS
IDLE AIR CONTROLS
IDLE SPEED CONTROL ACTUATORS
IGNITION BOOTS
IGNITION COIL TOWERS
IGNITION COILS
IGNITION CONTROL MODULES (ICM)
IGNITION SWITCHES
IGNITION TERMINALS
IGNITION WIRES, BOOTS, COIL TOWERS AND TERMINALS (SECONDARY)
IN-TANK FUEL STRAINERS
INERTIA FUEL SHUT-OFF SWITCHES
INTAKE AIR TEMPERATURE SENSORS
INTAKE MANIFOLDS
INTERCOOLERS
KNOCK SENSORS
LIQUID VAPOR SEPARATORS
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSORS
MASS AIR FLOW (MAF) SENSORS
METAL AIR MANIFOLDS AND PIPES
METAL AIR PIPES
MIX CONTROL SOLENOIDS
MOTOR MOUNTS
O-RINGS, GASKETS, SEALS AND SPRING LOCKS
O2 SENSORS
OIL PRESSURE SENDING UNITS
OIL PUMP PICK-UP SCREENS
OIL PUMPS
PARK NEUTRAL POSITION SWITCHES
PCV BREATHER ELEMENTS
PCV ORIFICES
PCV VALVES
PICK-UP ASSEMBLIES (INCLUDES MAGNETIC, HALL EFFECT AND
OPTICAL)
POWER STEERING PRESSURE SENSORS
POWERTRAIN CONTROL MODULES (PCM) AND PROM
POWERTRAIN CONTROL PROM
PRESSURIZED EXPANSION TANK CAPS
RADIATOR CAPS AND PRESSURIZED EXPANSION TANK CAPS
RADIATOR FAN BLADES
RADIATOR FAN CLUTCHES
RADIATORS
ROLL OVER VALVES
SEALING COMPOUNDS
SEALS
SECONDARY AIR INJECTION SYSTEM MANAGEMENT DEVICES
SENSORS AND ACTUATORS
SHROUDS, BAFFLES AND DEFLECTORS
SPARK PLUGS
SPRING LOCKS

Outer ring slipped out of
position ............... A ........... Require replacement.
Positioned incorrectly .. A . Require repair or replacement.
Rubber damping material
deteriorated ........... 1 ........... Suggest replacement.
Seal surface worn, causing
a leak ................. A . Require repair or replacement.
Threads damaged ......... A . Require repair or replacement.
Threads stripped (threads
missing) ............... A ........... Require replacement.









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HEATER CONTROL VALVES
HEATER CONTROL VALVE INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bypassed ................ A ............ Require replacement.
Coolant leak ............ A .. Require repair or replacement.
Malfunctioning .......... A ........... ( 1) Require repair or
replacement.
Missing ................. C ............ Require replacement.
Restricted .............. A .. Require repair or replacement.
Vacuum leak ............. A .. Require repair or replacement.
( 1) - Includes inoperative, intermittent operation, or
failure to perform all functions.









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HEATER CORES
HEATER CORE INSPECTION








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Condition Code Procedure
Air flow restriction .... A .. Require repair or replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bypassed ................ A .. Require repair or replacement.
Connection leaking ...... A .. Require repair or replacement.
Corroded ................ 1 .. Suggest repair or replacement.
Fins damaged, affecting
performance ............ A .. Require repair or replacement.
Fins damaged, not
affecting performance .. 2 .. Suggest repair or replacement.
Internal restrictions,

affecting performance .. A .. Require repair or replacement.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.









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HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS
NOTE: When replacing fuel lines and hoses, replace with product
that meets or exceeds OEM design specifications.
HOSE AND TUBE COUPLER, CONNECTOR AND CLAMP INSPECTION









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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Connected incorrectly ... A ................. Require repair.
Corroded, not reusable .. 1 ............ Suggest replacement.
Cracked ................. A ............ Require replacement.
Insufficient clamping
force, allowing hose to
leak ................... A .. Require repair or replacement.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Safety clip missing (not
leaking) ............... C ... Require replacement of safety
clip.
Stripped ................ A ............ Require replacement.









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HOSE CLAMPS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
HOSE CONNECTORS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
HOSE COUPLERS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
HOSES AND TUBES (FUEL LINES, RADIATOR, VACUUM, BY PASS,
HEATER, RECOVERY TANK AND OIL COOLERS)
HOSE AND TUBE (FUEL LINE, RADIATOR, VACUUM, BY PASS, HEATER,
RECOVERY TANK AND OIL COOLER) INSPECTION









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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Connected incorrectly ... A ................. Require repair.
Corroded, not reusable .. 1 ............ Suggest replacement.
Cracked ................. A ............ Require replacement.
Dry-rotted .............. 1 .. Suggest repair or replacement.
Hard .................... 1 .. Suggest repair or replacement.
Inner fabric (webbing)
damaged ................ A ............ Require replacement.
Insufficient clamping
force, allowing hose to
leak ................... A .. Require repair or replacement.
Leaking ................. A .. Require repair or replacement.
Maintenance intervals ... 3 ............ Suggest replacement.

check for accepted cleaning procedure.








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TUBE CLAMPS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
TUBE CONNECTORS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
TUBE COUPLERS
See HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS .
TUBES
See HOSES AND TUBES (FUEL LINES , RADIATOR, BY PASS, HEATER,
RECOVERY TANK AND OIL COOLERS).
TURBO CHARGERS
TURBO CHARGER INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Boost pressure
incorrect .............. A ........... ( 1) Require repair or
replacement.
Leaking ................. A .. Require repair or replacement.
Noisy ................... 2 .. Suggest repair or replacement.
Oil seal (internal)
leaking ................ A .. Require repair or replacement.
Vibrates ................ A .. Require repair or replacement.
( 1) - Boost pressure problems may be caused by other systems
or components.









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VACUUM CONNECTIONS
See VACUUM HOSES, TUBES AND CONNECTIONS (NON-METALLIC) .
VACUUM HOSES, TUBES AND CONNECTIONS (NON-METALLIC)
VACUUM HOSE, TUBE AND CONNECTION (NON-METALLIC) INSPECTION








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Condition Code Procedure
Leaking ................. A .. Require repair or replacement.
Melted .................. A ............ Require replacement.
Missing ................. C ............ Require replacement.
Oil-soaked (spongy) ..... 1 ............ Suggest replacement.

ECU is a digital microprocessor computer. Data sensors
provide the ECU with engine operating information in varying
electrical signals. ECU calculates this information and corrects
air/fuel ratio, ignition timing, and emission control as needed to
maintain efficient engine operation. Other ECU output signals control
upshift indicator light (manual transmission only), ignition module
dwell and A/C clutch operation.
UPSHIFT INDICATOR
On vehicles equipped with a manual transmission, ECU
controls upshift indicator light. Indicator light is normally
illuminated when ignition is turned on without engine running.
Indicator light is turned off when engine is started.
Indicator light will be illuminated during engine operation
in response to engine load and speed. If transmission is not shifted,
ECU will turn light off after 3 to 5 seconds. A switch located on
transmission prevents indicator light from being illuminated when
transmission is shifted to highest gear.
DATA SENSORS & SWITCHES
Manifold Absolute Pressure (MAP) Sensor
MAP sensor is located in engine compartment on firewall,
behind engine. MAP sensor monitors manifold vacuum via a vacuum line
from intake manifold to sensor.
MAP sensor supplies an electrical signal which keeps ECU
informed of manifold vacuum and barometric pressure conditions. This
information is combined with data supplied by other sensors to
determine correct air/fuel ratio.
Oxygen Sensor
Oxygen (O2) sensor is mounted in exhaust manifold where it
is exposed to exhaust gas flow. Its function is to monitor oxygen
content of exhaust gases and to supply ECU with a voltage signal
directly proportional to this content.
If oxygen content of exhaust gases is high (lean air/fuel
mixture), voltage signal to ECU is low. As oxygen content decreases
(mixture becomes richer), signal voltage increases.
In this way, ECU is kept constantly informed of air/fuel
ratio. ECU can then alter fuel injector "on" time, in response to
these signals, to obtain best air/fuel ratio of 14.7:1 under any
given operating conditions.
O2 sensor is equipped with a heating element that keeps
sensor at proper operating temperatures. Maintaining correct sensor
temperatures at all times guarantees a more accurate signal to ECU.
By using an O2 heater, fuel control system may also enter "closed
loop" operating mode sooner and maintain this mode, even during
periods of extended idle.
Temperature Sensors
There are 2 temperature sensors used on this system.
Manifold Air Temperature (MAT) sensor, mounted in intake manifold,
measures temperature of incoming air/fuel mixture and Coolant
Temperature Sensor (CTS), located on left side of cylinder block just
below the exhaust manifold, measures temperature of engine coolant.
Information provided by these 2 sensors to ECU allows ECU to
demand slightly richer air/fuel mixtures and higher idle speeds
during cold engine operation.
Throttle Position Sensor (TPS)
TPS is regulated by movement of throttle shaft. It is