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Jeep grand cherokee p0155 code p1494 - 2004 Jeep Grand Cherokee

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For the P0155 code, check the fuse for the O2 heater circuit.
The P1494 has to do with the EVAP leak detection pump pressure switch. Or the switch is faulty, or there is a large leak. Do you hear any hissing sounds under the jeep?

Posted on Sep 27, 2014

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Posted on Jan 02, 2017

  • 94 Answers

SOURCE: 2004 Jeep Grand Cherokee. Keeps stalling, engine

P0505 means the whole Idle Control system, not only the IAM. Check all related sensors (i.e. crankshaft sensor). Check with a voltmeter direct at the connector of the IAM if you get any signal. Remove the IAM from the TB, connect him, let someone switch your ignition key to ON. The IAM need to drive in/out for a short time to find the right position. Hold the IAM near a hard part, that they cant drive out completely! If IAM works fine, check the fuel pressure, check and clean your TB ( if not done yet). If that doesn't work, come back again please

Posted on Oct 27, 2009

  • 105 Answers

SOURCE: 2001 jeep cherokee has a p1494 code and a p0301

0301 is cyclinder 1 miss fire,check coil pack and spark plug,plug first,1494 is the fan relay,It's in the right front of the engine compartment. Kind of behind and below the RF headlamp and in front of and below the fuse box.
Easy to replace, just unplug it and plug the new one in.
The relay is the most common cause for that code with a no fan operation condition, we see it all the time.

Posted on Jan 31, 2010

  • 21 Answers

SOURCE: What does the code P1494 means on my 99 jeep grand

LEAK DETECTION PUMP SYSTEMS (P1494, P0442, P0455, P0456),

Posted on Jun 10, 2010

ZJLimited
  • 17970 Answers

SOURCE: code P1494

DTC P1494 - Leak Detection Pump Switch or Mechanical Fault

The causes are possibly an open or shorted switch sense circuit, a pump switch failure, or an open "fused ignition switch" output. First off, a model year 2001 is will still covered under the emissions warranty. That's federal law. So you should not have had to pay a penny for that repair since the Leak Detection Pump is an emission control device.

As is the Charcoal Canister. If that is bad there should be no charge for repair or replacement. I hope you saved the receipts because I think they owe you a bunch of money. If they give you an argument about it, call Chrysler and they will take care of it.

Now, are you ready to learn more about the Leak Detection Pump then you will ever need to know? Good! Here it is!

Leak Detection Pump (LDP) Operation And Diagnosis:

This article describes the theory of operation for the leak detection system. In addition, information is provided for each of the Diagnostic Trouble Codes (DTC's) as follows:

* P0442-Evap Leak Monitor 0.040" Leak Detected
* P0455-Evap Leak Monitor Large Leak Detected
* P0456-Evap Leak Monitor 0.020" Leak Detected
* P1486-Evap Leak Monitor Pinched Hose Found
* P1494-Leak Detection Pump SW Or Mechanical Fault
* P1495-Leak Detection Pump Solenoid Circuit

Introduction:
The evaporative emission system is designed to prevent the escape of fuel vapors from the fuel system. Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere.

Government regulations (remember I said that?) require on-board testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics.

During self-diagnostics, the Powertrain Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults. If the first checks pass, the PCM then uses the LDP to seal the vent valve and pump air into the system to pressurize it.

If a leak is present, the PCM will continue pumping the LDP to replace the air that leaks out. The PCM determines the size of the leak based on how fast/long it must pump the LDP as it tries to maintain pressure in the system.

EVAP Leak Detection System Components:
Service Port: Used with special tools like the Miller Evaporative Emissions Leak Detector (EELD) to test for leaks in the system.

EVAP Purge Solenoid: The PCM uses the EVAP purge solenoid to control purging of excess fuel vapors stored in the EVAP canister. It remains closed during leak testing to prevent loss of pressure.

EVAP Canister The EVAP canister stores fuel vapors from the fuel tank for purging. EVAP Purge Orifice: Limits purge volume.

EVAP System Air Filter: Provides air to the LDP for pressurizing the system. It filters out dirt while allowing a vent to atmosphere for the EVAP system.

Leak Detection Pump (LDP) Components:
The main purpose of the LDP is to pressurize the fuel system for leak checking. It closes the EVAP system vent to atmospheric pressure so the system can be pressurized for leak testing. The diaphragm is powered by engine vacuum. It pumps air into the EVAP system to develop a pressure of about 7.5' H20(1/4) psi. A reed switch in the LDP allows the PCM to monitor the position of the LDP diaphragm. The PCM uses the reed switch input to monitor how fast the LDP is pumping air into the EVAP system. This allows detection of leaks and blockage.

The LDP assembly consists of several parts. The solenoid is controlled by the PCM, and it connects the upper pump cavity to either engine vacuum or atmospheric pressure. A vent valve closes the EVAP system to atmosphere, sealing the system during leak testing. The pump section of the LDP consists of a diaphragm that moves up and down to bring air in through the air filter and inlet check valve, and pump it out through an outlet check valve into the EVAP system.

The diaphragm is pulled up by engine vacuum, and pushed down by spring pressure, as the LDP solenoid turns on and off. The LDP also has a magnetic reed switch to signal diaphragm position to the PCM. When the diaphragm is down, the switch is closed, which sends a 12 V (system voltage) signal to the PCM. When the diaphragm is up, the switch is open, and there is no voltage sent to the PCM. This allows the PCM to monitor LDP pumping action as it turns the LDP solenoid on and off.

LDP At Rest (Not Powered):
When the LDP is at rest (no electrical/vacuum) the diaphragm is allowed to drop down if the internal (EVAP system) pressure is not greater than the return spring. The LDP solenoid blocks the engine vacuum port and opens the atmospheric pressure port connected through the EVAP system air filter. The vent valve is held open by the diaphragm. This allows the canister to see atmospheric pressure.

Diaphragm Upward Movement:
When the PCM energizes the LDP solenoid, the solenoid blocks the atmospheric port leading through the EVAP air filter and at the same time opens the engine vacuum port to the pump cavity above the diaphragm. The diaphragm moves upward when vacuum above the diaphragm exceeds spring force. This upward movement closes the vent valve. It also causes low pressure below the diaphragm, unseating the inlet check valve and allowing air in from the EVAP air filter. When the diaphragm completes its upward movement, the LDP reed switch turns from closed to open.

Diaphragm Downward Movement:
based on reed switch input, the PCM de-energizes the LDP solenoid, causing it to block the vacuum port, and open the atmospheric port. This connects the upper pump cavity to atmosphere through the EVAP air filter. The spring is now able to push the diaphragm down. The downward movement of the diaphragm closes the inlet check valve and opens the outlet check valve pumping air into the evaporative system. The LDP reed switch turns from open to closed, allowing the PGM to monitor LDP pumping (diaphragm up/down) activity. During the pumping mode, the diaphragm will not move down far enough to open the vent valve.

The pumping cycle is repeated as the solenoid is turned on and off. When the evaporative system begins to pressurize, the pressure on the bottom of the diaphragm will begin to oppose the spring pressure, slowing the pumping action. The PCM watches the time from when the solenoid is de-energized, until the diaphragm drops down far enough for the reed switch to change from opened to closed. If the reed switch changes too quickly, a leak may be indicated. The longer it takes the reed switch to change state, the tighter the evaporative system is sealed. If the system pressurizes too quickly, a restriction somewhere in the EVAP system may be indicated.

Pumping Action:
During portions of this test, the PCM uses the reed switch to monitor diaphragm movement. The solenoid is only turned on by the PCM after the reed switch changes from open to closed, indicating that the diaphragm has moved down. At other times during the test, the PCM will rapidly cycle the LDP solenoid on and off to quickly pressurize the system. During rapid cycling, the diaphragm will not move enough to change the reed switch state. In the state of rapid cycling, the PCM will use a fixed time interval to cycle the solenoid.

The Charcoal Canister

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.

Vapor Canister:
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.

Hope helps (remember rated and comment this).

Posted on Jun 17, 2010

  • 327 Answers

SOURCE: 1999 Jeep Grand Cherokee.....My check engine light

Answer
Hi ,
The code refers to the leak detection pump that is part of the gasoline vapor control system which is for pollution minimization. It says either that the pump switch or mechanical operation is faulty. According to a Chrysler manual I have, you would find the pump, probably on the underside of the vehicle by tracing the hoses related to the vapor recovery tank that may be in the right front corner of the engine compartment (I don't know Jeep designs) and then check to see if the pump starts when you turn the ignition to the run position when the vehicle is cold. Then remove the vacuum hose side of the pump and see if it draws a vacuum. If it does, then the vacuum-detecting switch that detects that the pump operation is OK may be faulty. If the pump doesn't start or doesn't draw a vacuum then the power to the pump, the pump itself, or the vacuum line may be leaky. Finally, the powertrain controller could be at fault.
In any case, that is where the issue is, and it should not be a major issue if it is handled by a knowledgeable mechanic. But you could check it over yourself if you are so inclined. p.s. your best bet is to take it to a jeep dealer to get it fixed hope this helps please dont forget to rate my solution

Posted on Sep 30, 2010

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2 Answers

Que significa codigo p1494


P1494 Leak detection pump pressure switch or mechanical fault

Jul 01, 2014 | 1999 Jeep Grand Cherokee

2 Answers

What else, Check Engine Light, P0505, p0135, p0155, p1494 codes?


You can not work on a vehicle as your doing

Your checking for generic codes only & throwing
parts at it

You get a couple possible worn or failed parts & have
a few less codes

There is no need to clear ALL Data every time you change a part

You need to STOP

You need professional scan tool software to look at ALL data & go for a road test first

You keep clearing stored data ,so now the process will take longer

You work one code & one system at a time

NO PARTS get replaced that are not tested & found to fail
a test,thus a worn out part.

You need both Factory Emission & Diagnostic Manual, as well
as Wiring Diagram Book-- BEFORE-- you can even walk to the vehicle (Helm.Com)

You have nothing to go by,no system knowledge & no trouble charts,& no wiring diagrams to start your testing

If you got no scan tool & no volt meter & no oscilloscope,
your done,vehicles have to be tested to find a problem,any
problem,resolve it & continue on.

May 19, 2014 | 2004 Jeep Grand Cherokee

1 Answer

Check engine light came on code P0505, P0135, P0155, P1494.


kia ora Mark , greetings , sorry bro these code things are beyond me ive been driving around with a p0161. i believe its a bank2 down stream sensor for 2 years , maybe you can help me , 2002 grand cherokee 4.7 Ho , do you know what brand of sensor or part numbers i need , an idea of cost for same . i forgot to mention i am in New Zealand and auto parts are so much more expensive here , no idea at all , much help needed everyone thank you all , hope you get sorted Mark cheers mate

May 19, 2014 | 2002 Jeep Grand Cherokee

1 Answer

What does the code P1494 means on my 99 jeep grand cherokee


LEAK DETECTION PUMP SYSTEMS (P1494, P0442, P0455, P0456),

Jun 10, 2010 | 2001 Jeep Grand Cherokee

1 Answer

P0155 code


P0155-02 sensor 2/1 heater failure. When monitored with battery voltage great than 10.5 volts at cold start ECT lessthank 14.7F battery temperature sensor equal to or less than 27F and engine idle for at least 12 seconds.Thanks

Feb 24, 2010 | 2004 Jeep Grand Cherokee

2 Answers

Engine light on with code 1494runs ok for now but light want stay off when i have it taken off, was told it was sensor to motor, but that there was four different ones and they don't know which one it...


P1494 means Leak Detection Pump Switch or Mechanical Fault - This code appears when there's an issue with the EVAP System (fuel tank fumes) This can be caused by a improperly secured gas cap, faulty gas cap, crack in the vacuum line, etc.

Sep 17, 2009 | 2001 Jeep Grand Cherokee

1 Answer

Codes for durango p0443-0753-1765-1494


danbalue, a code P1765 means Transmission 12V Supply Relay Control Conditions and P1494 means EVAP LDP Pressure Switch Fault Conditions.

I found info on the following codes:
P0443 - http://www.obd-codes.com/p0443
P1494 - http://www.check-engine-light.com/dodge

Good luck.

Sep 05, 2009 | 1999 Jeep Grand Cherokee

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