1988 JEEP CHEROKEE checking oil

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Page 928 of 1378

JEEP CHEROKEE 1988 Service Repair Manual PO W ER S TE ER IN G G EN ER AL S ER VIC IN G

1988 J e ep C hero ke e
1988 STEERING
Jeep Power Steering General Servicing
Cherokee, Comanche, Grand Wagoneer, Pickup

Page 943 of 1378

JEEP CHEROKEE 1988 Service Repair Manual To test crankcase ventilation system, start engine and allow
it to reach normal operating temperature. Make sure engine is idling
at normal curb idle, and perform following checks:
1

To test crankcase ventilation system, start engine and allow
it to reach normal operating temperature. Make sure engine is idling
at normal curb idle, and perform following checks:
1) Remove PCV valve from its mounting. If valve is
functioning properly, hissing noise will be heard as air passes
through it. Strong vacuum should be felt when your finger is placed
over valve inlet.
2) While finger is over inlet, check for presence of vacuum
leaks in hose line and at all connections. Reinstall PCV valve,
remove crankcase air inlet hose at air cleaner.
3) Loosely hold piece of stiff paper over opening at end of
inlet hose. Paper should be sucked against hose opening with
noticeable force after sufficient time has elapsed for crankcase
pressure to lower (usually about a minute). For final check, stop
engine, remove PCV valve and shake it. Metallic clicking noise should
be heard, indicating valve is free.
4) If system passes both engine running and stopped tests,
it is functioning properly. No further tests are required. If it has
failed either test, replace appropriate components and retest. If it
does not pass on second try, clean system.
MAINTENANCE
Engine may idle slow or rough due to clogged ventilator
valve or system. Therefore, never adjust carburetor idle without
first checking valve and system.
If ventilator valve or system becomes clogged, all crankcase
ventilation will stop, and serious engine damage could result.
Although following manufacturers' service procedures give
specific intervals, it is recommended the crankcase ventilation
system be checked more frequently if vehicle is operated under severe
conditions (extreme dust, prolonged idling, trailer hauling or short
trips in cold weather).
PCV VALVE
Replace PCV valve every 30,000 miles. Valve is located on
rocker arm cover of 4-cylinder, 6-cylinder and V6 models and on
intake manifold of V8 models.
FILTER ELEMENT
Clean filter element every 30,000 miles. Filter is located
inside air cleaner of 4-cylinder, 6-cylinder and V6 models and in oil
filler cap of V8 models.

Page 1215 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual \003 TR AN SM IS SIO N S ER VIC IN G - A /T 1988 J e ep C hero ke e 1988 Automatic Transmission Servicing JEEP LUBRICATION SERVICE INTERVALS Trans$

\003
TR AN SM IS SIO N S ER VIC IN G - A /T

1988 J e ep C hero ke e
1988 Automatic Transmission Servicing
JEEP
LUBRICATION
SERVICE INTERVALS
Transmission
Check fluid level and condition of fluid at each engine oil
change. Under normal, light duty operating conditions, change fluid,
replace filter and adjust bands every 2 yrs. or 25,000 miles. Under
heavy duty service, change fluid, replace filter and adjust bands
every 12 months or 12,500 miles.
Transfer Case
Check transfer case fluid every 12,000 miles and replace
fluid every 30,000 miles.
CHECKING FLUID LEVEL
Transmission
Park vehicle on a level surface and apply parking brake.
With engine idling at normal operating temperature, move transmission
selector lever through all gears, ending in "N" ("P" for AW-4
transmission). Check fluid level. Fluid level should be between
"FULL" and "ADD ONE PINT" mark on dipstick. Add fluid as needed. DO
NOT overfill.
Transfer Case
Remove fill plug. Check oil level. If level is not up to
fill plug opening, add lubricant until it is.
RECOMMENDED FLUID
Both transmissions and transfer cases use DEXRON-II ATF.
FLUID CAPACITY
NOTE: Transmission and converter capacities are approximate. Fluid
level should always be determined by reading on dipstick,
rather than amount of fluid added.
TRANSMISSION REFILL CAPACITIES
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Application Quantity
All Models
Including Converter ................................ 8.5 qts. (8.0L)\
Without Converter .................................. 4.3 qts. (4.0L)\
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TRANSFER CASE REFILL CAPACITIES\
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Application Capacity
Model 207 ............................................ 4.5 pts. (2.1L)\
Model 208 ............................................ 6.0 pts. (2.8L)\

Page 1220 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual \003 TR AN SM IS SIO N S ER VIC IN G - M /T 1988 J e ep C hero ke e 1988 MANUAL TRANSMISSION SERVICING Jeep Cherokee, Comanche, Grand Wagoneer, Pickup, Wagoneer,$

Page 1225 of 1378

JEEP CHEROKEE 1988 Service Repair Manual widening the gap to 1/4-3/8".

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

��

widening the gap to 1/4-3/8".

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

\
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\b
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\

GOOD SPARK NO SPARK
\
\b \
\b
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\

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\

* If plug sparks, driveability * Remove coil wire from the

problem is most likely NOT distributor and attach the

in the ignition system. modified spark plug. Ground

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\b
the plug and crank engine
while checking for spark.
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\b
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GOOD SPARK NO SPARK
\
\b \
\b
\
\
\

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\

* If plug has a good spark, * Proceed to the IGNITION

the problem is in the plug PRIMARY TROUBLE SHOOTING

wires, distributor cap, or CHECK CHART below in this

rotor. Replace components article.

as necessary.
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\b

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\b

Ignition Primary Trouble Shooting Chart
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START: Visually inspect primary ignition wires for

broken, frayed, split, or cut wires. Also check

for loose, corroded, or disconnected connectors.

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\b
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\

OK NOT OK
\b \b
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\

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* Check that battery voltage * Repair or replace damaged

is at least 11.5 volts. components as necessary.

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\b
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\b
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NOT OK OK
\b \b
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\

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* Replace or recharge the * Check for battery voltage

battery. at the positive terminal of

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\b
the coil.
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\b
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\

OK NOT OK
\b \b
\
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\

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* Check air Gap of the Pick-Up * Check resistance of ballast

coil in the distributor. resistor (if used) for the

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\b
correct resistance value.
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\b
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Page 1249 of 1378

$JEEP CHEROKEE 1988 Service Repair Manual ��\ ��\ ��\ ��\ ��\ ��\ ��\b ��\ ��\ � ��\$

\
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\b
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\

\

OK NOT OK
\b \b
\
\
\

\
\

* To test secondary ignition * Repair or replace

system, modify a Spark Plug damaged components

by attaching a ground wire as necessary

to the body of the plug and
\
\
\b

widening the gap to 1/4-3/8".

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

\
\
\
\b
\
\
\
\
\
\
\

GOOD SPARK NO SPARK
\
\b \
\b
\
\
\

\
\
\

* If plug sparks, driveability * Remove coil wire from the

problem is most likely NOT distributor and attach the

in the ignition system. modified spark plug. Ground

\
\
\
\b
the plug and crank engine
while checking for spark.
\
\
\
\b
\
\
\
\
\
\
\

GOOD SPARK NO SPARK
\
\b \
\b
\
\
\

\
\
\

* If plug has a good spark, * Proceed to the IGNITION

the problem is in the plug PRIMARY TROUBLE SHOOTING

wires, distributor cap, or CHECK CHART below in this

rotor. Replace components article.

as necessary.
\
\
\
\b

\
\
\
\b

Ignition Primary Trouble Shooting Chart
\
\
\
\
\
\

START: Visually inspect primary ignition wires for

broken, frayed, split, or cut wires. Also check

for loose, corroded, or disconnected connectors.

\
\
\
\
\
\
\b
\
\
\
\
\

\

OK NOT OK
\b \b
\
\
\

\
\
\

* Check that battery voltage * Repair or replace damaged

is at least 11.5 volts. components as necessary.

\
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\
\b
\
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\
\b
\
\
\
\
\
\

NOT OK OK
\b \b
\
\
\

\
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\

* Replace or recharge the * Check for battery voltage

battery. at the positive terminal of

\
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\
\b
the coil.
\
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\
\b

Page 1318 of 1378

JEEP CHEROKEE 1988 Service Repair Manual the types of injector circuits that your noid lights are designed for.
There are three. They are:
* Systems with a voltage controlled injector driver. Another
way to say it: The noid l

the types of injector circuits that your noid lights are designed for.
There are three. They are:
* Systems with a voltage controlled injector driver. Another
way to say it: The noid light is designed for a circuit with
a "high" resistance injector (generally 12 ohms or above).
* Systems with a current controlled injector driver. Another
way to say it: The noid light is designed for a circuit with
a low resistance injector (generally less than 12 ohms)
without an external injector resistor.
* Systems with a voltage controlled injector driver and an
external injector resistor. Another way of saying it: The
noid light is designed for a circuit with a low resistance
injector (generally less than 12 ohms) and an external
injector resistor.
NOTE: Some noid lights can meet both the second and third
categories simultaneously.
If you are not sure which type of circuit your noid light is
designed for, plug it into a known good car and check out the results.
If it flashes normally during cranking, determine the circuit type by
finding out injector resistance and if an external injector resistor
is used. You now know enough to identify the type of injector circuit.
Label the noid light appropriately.
Next time you need to use a noid light for diagnosis,
determine what type of injector circuit you are dealing with and
select the appropriate noid light.
Of course, if you suspect a no-pulse condition you could plug
in any one whose connector fit without fear of misdiagnosis. This is
because it is unimportant if the flashing light is dim or bright. It
is only important that it flashes.
In any cases of doubt regarding the use of a noid light, a
lab scope will overcome all inherent weaknesses.
OVERVIEW OF DVOM
A DVOM is typically used to check injector resistance and
available voltage at the injector. Some techs also use it check
injector on-time either with a built-in feature or by using the
dwell/duty function.
There are situations where the DVOM performs these checks
dependably, and other situations where it can deceive you. It is
important to be aware of these strengths and weaknesses. We will cover
the topics above in the following text.
Checking Injector Resistance
If a short in an injector coil winding is constant, an
ohmmeter will accurately identify the lower resistance. The same is
true with an open winding. Unfortunately, an intermittent short is an
exception. A faulty injector with an intermittent short will show
"good" if the ohmmeter cannot force the short to occur during testing.
Alcohol in fuel typically causes an intermittent short,
happening only when the injector coil is hot and loaded by a current
high enough to jump the air gap between two bare windings or to break
down any oxides that may have formed between them.
When you measure resistance with an ohmmeter, you are only
applying a small current of a few milliamps. This is nowhere near
enough to load the coil sufficiently to detect most problems. As a
result, most resistance checks identify intermittently shorted
injectors as being normal.
There are two methods to get around this limitation. The
first is to purchase an tool that checks injector coil windings under

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