2004 JEEP GRAND CHEROKEE low oil pressure

Defrosters
Check operation by selecting the defrost mode and place
the blower control on high speed. You should feel the air
directed against the windshield.
Safety Checks You Should Make Outside The
Vehicle
Tires
Examine tires for excessive tread wear or uneven wear
patterns. Check for stones, nails, glass, or other objects
lodged in the tread. Inspect for tread cuts or sidewall
cracks. Check wheel nuts for tightness and tires (includ-
ing spare) for proper pressure.
Lights
Have someone observe the operation of all exterior lights
while you work the controls. Check turn signal and high
beam indicator lights on the instrument panel.
Fluid Leaks
Check area under vehicle after overnight parking for fuel,
coolant, oil or other fluid leaks. Also, if gasoline fumes
are detected, the cause should be located and corrected
immediately.
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 53
2

7. Oil Pressure Gage
Indicates the engine oil pressure. This gage does
not measure oil level. Pressure varies with engine
speed, temperature, and oil viscosity. Normal oil pressure
will be midway between the lowest and highest limit
marks.
8. Sentry Key Indicator Light Ð If Equipped
Refer to ªSentry Key Immobilizer Systemº in
Section 2 of this manual for more information.
9. Malfunction Indicator Light
This light is part of an onboard diagnostic system
called OBD II which monitors engine and auto-
matic transmission control systems. This light
will illuminate when the ignition is in the ON position
before engine start. If the bulb does not come on when
turning the ignition key from OFF to ON, have the
condition checked promptly.Certain conditions such has a loose or missing gas cap,
poor fuel quality, etc. may illuminate the light after
engine start. The vehicle should be serviced if the light
stays on through several typical driving cycles. In most
situations, the vehicle will drive normally and will not
require towing.
When the engine is running, the ªMalfunction Indicator
Lightº may flash to alert of serious conditions that could
lead to immediate loss of power or severe catalytic
converter damage. The vehicle should be serviced as
soon as possible if this occurs.
10. Cruise Indicator Light
This indicator lights when the electronic speed
control system is turned ON.
11. Check Gages Warning Light
This light illuminates when the voltmeter, oil
pressure, or temperature gages indicate a reading
130 UNDERSTANDING YOUR INSTRUMENT PANEL

either too high or too low. Examine the gages carefully,
and follow the instructions above for each indicated
problem.
NOTE:When the ignition switch is turned to OFF, the
fuel gage, voltmeter, oil pressure, and temperature gages
will not show any readings. When the engine is not
running, turn the ignition switch to ON to obtain accu-
rate readings.
12. Part Time Indicator Light
This light alerts the driver that the vehicle is in
the PART TIME four±wheel drive mode, and
the front and rear driveshafts are mechanically
locked together forcing the front and rear wheels to rotate
at the same speed.
13. Transmission Over Temperature Warning Light
This light indicates that there is excessive transmis-
sion fluid temperature that might occur with severe
usage such as trailer towing or snow plowing. If this lightcomes on, stop the vehicle and run the engine at idle or
faster, with the transmission in N (Neutral) until the light
goes off.
14. Temperature Gage
Indicates engine coolant temperature. Any read-
ing within the normal range indicates that the
cooling system is operating satisfactorily.
The gage pointer will likely indicate a higher temperature
(above center scale) when driving in hot weather, up
mountain grades, or when towing a trailer. It should not
be allowed to exceed the upper limits of the normal
operating range.
If the pointer rises to the 260É (Hot) mark, pull over and
stop the vehicle. Do not turn the engine off. Idle the
vehicle with the air conditioning turned off, until the
pointer drops back into the normal range.
UNDERSTANDING YOUR INSTRUMENT PANEL 131
4

seatback or completely removed from the vehicle. It can
also be kneeled down upon and used as ground cover
to prevent clothing from getting soiled.
3. Remove the nut and tire.To Replace the Spare Tire
1. Place the tire into the rear compartment with the
wheel facing upward:
a. Replace the hold-down nut.
b. Reinstall the cover by inserting the hinges through
the carpet into the brackets at about a 30 degree angle
and lower into position. Press down to lock the cover
in position.
2. Your vehicle is equipped with either a temporary-use
spare tire or a conventional spare tire. Maintain the
temporary-use spare tire pressure at 60 psi (420 kPa), and
the conventional spare at 33 psi (228 kPa).
240 WHAT TO DO IN EMERGENCIES

CAUTION!
Overfilling or underfilling the crankcase will cause
aeration or loss of oil pressure. This could damage
your engine.
Change Engine Oil
Road conditions as well as your kind of driving affect the
interval at which your oil should be changed. Check the
following to determine if any apply to you:
²Day or night temperatures are below 32ÉF (0ÉC)
²Stop and go driving
²Extensive engine idling
²Driving in dusty conditions
²Short trips of less than 10 miles (16.2 km)
²More than 50% of your driving is at sustained high
speeds during hot weather, above 90ÉF (32ÉC)
²Trailer towing
²Taxi, Police, or delivery service (Commercial Service)
²Off road or desert operation
²If equipped for and operating with E-85 (ethanol) fuel
IfANYof these apply to you, then change your engine oil
every 3,000 miles (5 000 km) or 3 months, whichever
comes first, and follow the maintenance recommenda-
tions in ªMaintenance Schedule B.º
If none of these apply to you, then change your engine oil
every 6,000 miles (10 000 km) or 6 months, whichever
comes first.
NOTE:Under no circumstances should oil change in-
tervals exceed 6,000 miles (10 000 km) or 6 months
whichever comes first.
258 MAINTAINING YOUR VEHICLE