Top 10 2002 Jeep Wrangler Questions & Answers

should be part of the prndl switch which is on the trans just behind where the linkage is fastened

When the gauge is at 0, is there any noise from the engine (tick, knock etc?) I would have someone put a mechanical gauge on there and read true pressure.Your driving pressure seems OK but if the low number is "real" something is wrong!

2002 Jeep Wrangler 4WD 2.5L SFI 4cyl



Fig. The engine serial number is located at the right front side of the engine block (models 1997-2005)

I hope help you wth this; good luck (remember rated this help).

P0302 means number two cylinder has a misfire, due to possibly a spark plug, spark plug wire, ignition coil, fuel injector or something mechanical in the engine like a bad valve, valve spring etc. Start at the front of the engine, where all the accessories are mounted(alternator, power steering pump, etc) then count each each spark plug from left to right in normal order. The cylinder to the left will be 1, and the cylinder to the far right will be 4. When you locate number 2 cylinder, check the plug wire for damage. remove the spark plug and inspect it for wear. A new set of spark plugs and wires will probably fix your problem. Otherwise it may me a coil pack or ignition module. Hope this helps.

If fuse is good, then turn switch on, and take a voltmeter or test light and test power to the motor. If there is power, then motor is bad. If no power, than switch or relay is bad.

With the jeep running put a volt meter on the battery and it should be reading above 13 volts if not replace the altinator it isn't charging.You can check the fuse for the altinator first if not charging but most likely the altinator is bad.

Same problem on my 2001 TJ. Replaced cap, passed smoke test, supposed pinched hose fixed etc; light kept coming back on usually right after a cold start every other week or so. Three months later after trip to dealer and $367, it was due to an intermittenent evap cannister purge solenoid.

THE P0455 CODE POSSIBLE CAUSES ARE

• Leak at Gas Cap
• Vehicle History and Service Bulletin Investigation
• Visual and Physical Inspection
• Verify Evaporative Emission Leak
• EVAP Purge Solenoid Operation
• Intermittent LDP Monitor Failure
• Evaporative Emission Leak Detection
• Gas Cap
• LDP Component Leak

WHAT ENGINE DIAGRAMS I HAVE IS BELOW WITH DEFINITIONS

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On 4.0L 6 cylinder engines, a molded vacuum tube connects manifold vacuum to top of cylinder head (valve) cover at dash panel end. The vacuum fitting contains a fixed orifice of a calibrated size. It meters the amount of crankcase vapors drawn out of the engine.

On 2.5L 4 cylinder engines, a fitting on drivers side of cylinder head (valve) cover contains the metered orifice. It is connected to manifold vacuum.

A fresh air supply hose from the air cleaner is connected to front of cylinder head cover on 4.0L engines. It is connected to rear of cover on 2.5L engines.

When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during combustion.

EVAP/PURGE SOLENOID
The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM cycles (energizes and de-energizes) the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time that the solenoid is energized. The PCM adjusts solenoid pulse width based on engine operating condition.

FUEL FILLER CAP
The plastic fuel tank filler tube cap is threaded onto the end of the fuel fill tube Certain models are equipped with a 1/4 turn cap.

The loss of any fuel or vapor out of fuel filler tube is prevented by the use of a pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vacuum will also be released at predetermined values. This cap must be replaced by a similar unit if replacement is necessary This is in order for the system to remain effective.

CAUTION: Remove fill cap before servicing any fuel system component to relieve tank pressure. If equipped with a California emissions package and a Leak Detection Pump (LDP) , the cap must be tightened securely. If cap is left loose, a Diagnostic Trouble Code (DTC) may be set.

LEAK DETECTION PUMP
The Leak Detection Pump (LDP) is used only with certain emission packages

The LDP is a device used to detect a leak in the evaporative system.

The pump contains a 3 port solenoid, a pump that contains a switch, a spring loaded canister vent valve seal, 2 check valves and a spring/diaphragm.

Immediately after a cold start, engine temperature between 40 °F and 86 °F , the 3 port solenoid is briefly energized. This initializes the pump by drawing air into the pump cavity and also closes the vent seal. During non-test test conditions, the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel position. The vent seal will remain closed while the pump is cycling. This is due to the operation of the 3 port solenoid which prevents the diaphragm assembly from reaching full travel. After the brief initialization period, the solenoid is de-energized, allowing atmospheric pressure to enter the pump cavity. This permits the spring to drive the diaphragm which forces air out of the pump cavity and into the vent system. When the solenoid is energized and de-energized, the cycle is repeated creating flow in typical diaphragm pump fashion. The pump is controlled in 2 modes:

Pump Mode: The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test time.

Test Mode: The Solenoid Is Energized With A Fixed Duration Pulse. Subsequent fixed pulses occur when the diaphragm reaches the switch closure point.

The spring in the pump is set so that the system will achieve an equalized pressure of about 7.5 inches of water.

When the pump starts, the cycle rate is quite high. As the system becomes pressurized pump rate drops. If there is no leak the pump will quit. If there is a leak, the test is terminated at the end of the test mode.

If there is no leak, the purge monitor is run. If the cycle rate increases due to the flow through the purge system, the test is passed and the diagnostic is complete.

The canister vent valve will unseal the system after completion of the test sequence as the pump diaphragm assembly moves to the full travel position.

VACUUM LINES
A vacuum schematic for emission related items can be found on the VECI label. Refer to Vehicle Emission Control Information (VECI) Label for label location


VAPOR CANISTER
The evaporative (EVAP) canister is located in the engine compartment on the left inner fender.

A maintenance free, EVAP canister is used on all vehicles. The EVAP canister is filled with granules of an activated carbon mixture. Fuel vapors entering the EVAP canister are absorbed by the charcoal granules.

Fuel tank pressure vents into the EVAP canister. Fuel vapors are temporarily held in the canister until they can be drawn into the intake manifold. The duty cycle EVAP canister purge solenoid allows the EVAP canister to be purged at predetermined times and at certain engine operating conditions.

ONE WAY TO CLEAR ENGINE CODES WITH OUT HAVING A DIAGNOSTIC COMPUTER IS UN PLUG THE BATTERY AND LEAVE IT SIT FOR ROUGHLY 20 MINUTE AND REHOOK UP THIS MIGHT CLEAR THE CODES WITH OUT A COMPUTER.. BUT IF THE PROBLEM ISN'T FIXED THE CODES WILL SHOW AGAIN..


HOPE THIS HELPS

The ASD is what powers the fuel pump relay you need to check the engine fuse box junction for open fuse especially the fuel pump fuse and the ignition fuse. Get the ASD power corrected and the fuel pump injectors coil and reference will be back in action,check the fuse especially fuse No.23

great question, wana Read the shop manual for free, ?
it answers all this, its a rolling encrypted secret code.
bad idea
says it all, YOU DID.
now the system sees you hacking,
and bricks it.
there is only 1 fix. dealer time. or a shop with same tools.

they must be all married or they self brick
its also law here in use, DOT bs, rules.
not jeeps fault < GOV BS.

page 8e-1 , on, read. in jeep SM.

When a PCM (JTEC) and the SKIM are replaced
at the same time, perform the following steps in
order:
(1) Program the new PCM (JTEC).
(2) Program the new SKIM.
(3) Replace all ignition keys and program them to
the new SKIM.
PROGRAMMING THE PCM (JTEC)
The SKIS Secret Key is an ID code that is unique
to each SKIM. This code is programmed and stored
in the SKIM, the PCM, and the ignition key transponder
chip(s). When replacing the PCM, it is necessary
to program the secret key into the new PCM
using the DRBIIIt scan tool. Perform the following
steps to program the secret key into the PCM.
(1) Turn the ignition switch to the On position
(transmission in Park/Neutral).
(2) Use the DRBIIIt and select THEFT ALARM,
SKIM, then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
(5) Select ENTER to update PCM VIN.
NOTE: If three attempts are made to enter secured
access mode using an incorrect PIN, secured
access mode will be locked out for one hour. To
exit this lockout mode, turn the ignition switch to
the ON position for one hour, then enter the correct
PIN. (Ensure all accessories are turned off. Also
monitor the battery state and connect a battery
charger if necessary).
(6) Press ENTER to transfer the secret key (the
SKIM will send the secret key to the PCM).

(7) Press PAGE BACK to get to the Select System
menu and select ENGINE, MISCELLANEOUS, and
SRI MEMORY CHECK.
(8) The DRBIIIt will ask, “Is odometer reading
between XX and XX?” Select the YES or NO button
on the DRBIIIt. If NO is selected, the DRBIIIt will
read, “Enter Odometer Reading (From I.P. odometer)”.
Enter the odometer reading from the instrument
cluster and press ENTER.
PROGRAMMING THE SKIM
(1) Turn the ignition switch to the On position
(transmission in Park/Neutral).
(2) Use the DRBIIIt and select THEFT ALARM,
SKIM, then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Program the vehicle four-digit PIN into SKIM.
(5) Select COUNTRY CODE and enter the correct
country.
NOTE: Be sure to enter the correct country code. If
the incorrect country code is programmed into
SKIM, it cannot be changed and the SKIM must be
replaced.
(6) Select YES to update VIN (the SKIM will learn
the VIN from the PCM).
(7) Press ENTER to transfer the secret key (the
PCM will send the secret key to the SKIM).
(8) Program ignition keys to the SKIM.
NOTE: If the PCM and the SKIM are replaced at the
same time, all vehicle ignition keys will need to be
replaced and programmed to the new SKIM.
PROGRAMMING IGNITION KEYS TO THE SKIM
(1) Turn the ignition switch to the On position
(transmission in Park/Neutral).
(2) Use the DRBIIIt and select THEFT ALARM,
SKIM, then MISCELLANEOUS.
(3) Select PROGRAM IGNITION KEY’S.
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
NOTE: A maximum of eight keys can be learned to
each SKIM. Once a key is learned to a SKIM it (the
key) cannot be transferred to another vehicle.
(5) Obtain ignition keys to be programmed from
the customer (8 keys maximum).
(6) Using the DRBIIIt, erase all ignition keys by
selecting MISCELLANEOUS, and ERASE ALL CURRENT
IGN. KEYS.
(7) Program all of the ignition keys.
If ignition key programming is unsuccessful, the
DRBIIIt will display one of the following messages:
² Programming Not Attempted - The DRBIIIt
attempts to read the programmed key status and
there are no keys programmed into SKIM memory.
² Programming Key Failed (Possible Used
Key From Wrong Vehicle) - SKIM is unable to program
an ignition key transponder due to one of the
following:
² The ignition key transponder is faulty.
² The ignition key transponder is or has been
already programmed to another vehicle.
² 8 Keys Already Learned, Programming Not
Done - The SKIM transponder ID memory is full.
² Learned Key In Ignition - The ID for the ignition
key transponder currently in the ignition lock
cylinder is already programmed in SKIM memory.
end quote.