Jeep Grand Cherokee:

Starting

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#1 5/25/2010 6:24 PM

alln
New member
Registered: 5/25/2010
Posts: 1

Starting

Turn key in my 2005 Grand Cherokee and get nothing. Go back later and it will start like it's suppose to and may for a month. Then do it again.

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#2 5/26/2010 12:53 AM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Starting

When you say you turn the key and get nothing. Are all the lights out? Is the battery dead? When you say come back later is it minutes or hours. Do you have a factory installed alarm system? If you do there is a service bulletin for a bad hood switch that will prevent the car from starting, this may apply to your car. The service bulletin number is 08-014-05 it is dated February 17, 2005. 

You should have a chip in the key; it is for the Sentry key immobilizer system (SKIS). Sometimes the key cylinder cannot read the frequency of the chip in the key and will not allow the car to start. If you wait about five minutes you should try the key again. Most likely it will start the second time. Is the battery good in your remote?

Having the system scanned by your dealer or local professional is probably a good idea. This is an interment problem and will be hard to diagnose. The trouble codes they may get out of the computer memory can guide them to the problem area.They may have run into this problem before and may be familiar with the symptoms.

These are just two common suggestions. Having an interment problem can be anything from a loose or corroded connection to a communication failure between modules to parts failure in the ignition and starter circuits.


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#3 6/6/2010 2:45 PM

nomels
New member
Registered: 6/6/2010
Posts: 1

Re: Starting

I have been experiencing the same/similar problem with 05 Jeep Grand Cherokee (36,000 miles) as well.   Last summer, I drove about 3 miles, turned the car off, came back 10 minutes later, car wouldn’t start.  I called AAA, when they showed up  45 minutes later, the tech was just looking around and it started.

About 2 months ago, I drove about 10 miles, turned the car off, came back 5 minutes later, car wouldn’t  start.  I called AAA and tried to start it during the 1.5 hours I was waiting for them to arrive.  It did not start, I had it towed to a local mechanic.  The next morning, I stopped by and tried to start the car and it started (mechanic had not looked at it). 

The first time, I had it towed to a Jeep dealer.  They could not replicate the problem, they checked and cleaned connections, ran diagnostics, checked the battery, and found nothing.  The second time, I had it towed to a local mechanic.  He ran diagnostics and could not find anything wrong either.  Both agreed that it was not the starter. 

When it does not start, all I get is a click noise (one click noise per key turn).   The lights, windows, radio, all work fine. 

Yesterday, I was trying to unlock the car using the keyless remote and it would not unlock.  Finally, after I walked around the car pushing the button it opened.  The battery is fairly new in it.  I don’t know if this is related or not, but someone told me that maybe the key isn’t communicating with the car and this would cause it not to unlock and sometimes not start.  I bought this key less than a year ago because the one that I got with the car (I bought the car used last summer) did not seem to work well with unlocking/locking the doors.  I read service bulletin, 08-014-05, but this seems to be for a remote car starter which I don’t have. 

I have read other forums where people with 2005 Jeep Cherokees seem to have this not starting problem, but there doesn’t seem to be a definite resolution.  I would have thought the Jeep dealer would have seen it before, but they really had no idea.  Is there a particular module in the car that talks with the key?  I think you’re right, both places have told me they can’t tell what it is if they can’t see it for themselves.  But the post from TechHelp2 mentions that the computer may store problem codes, but I guess this is not the case for my problem since both places say they cannot determine.

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#4 6/6/2010 4:16 PM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Starting

This is obviously an annoying problem and is more frustrating when you bring in the vehicle for the problem and nobody can find the problem because the vehicle starts and no problem found.

The scan tool used to diagnose the problem is a very complex computer that has the ability to communicate with all modules of the car. When going into the problem module you can retrieve trouble codes from that module. If the scan tool is used to just look at trouble codes it will display the OBD 2 codes not body control codes.

The system in the vehicle is very complex where all modules communicate with each other. I'm listing the system operation for the remote door lock system to show you how complex the system is and why the ordinary mechanic can't fix these kinds of problems.

In this information it will give you tips on how to recognize the problem by viewing the appropriate dash lights and how they flash.

OPERATION:

The Sentry Key Remote Entry Module (SKREEM) is sometimes referred to as the Wireless control module (WCM). The SKREEM is the primary component of the Sentry Key Immobilizer System (SKIS). It is also the receiver for the Remote Keyless Entry (RKE) system and the Tire Pressure Monitoring System. The SKREEM is located on the instrument panel, just to the right of the steering column, mounted around the ignition lock cylinder housing and is concealed beneath the instrument panel. The molded black plastic housing for the SKREEM has an integral molded plastic halo-like antenna ring. When the SKREEM is properly installed, the antenna ring is oriented around the circumference of the ignition lock cylinder housing.

A single integral connector is located next to the antenna ring on the SKREEM housing. The SKREEM is connected to the vehicle electrical system through the instrument panel wire harness. The SKREEM cannot be adjusted or repaired. If faulty or damaged, the entire SKREEM unit must be replaced.

The Sentry Key Remote Entry Module (SKREEM) contains a Radio Frequency (RF) transceiver and a microprocessor. The SKREEM transmits RF signals to, and receives RF signals from the Sentry Key transponder through a tuned antenna enclosed within the molded plastic antenna ring integral to the SKREEM housing. If this antenna ring is not mounted properly around the ignition lock cylinder housing, communication problems between the SKREEM and the transponder may arise. These communication problems will result in Sentry Key transponder-related faults. The SKREEM also serves as the Remote Keyless Entry (RKE) RF receiver. The SKREEM communicates over the Controller Area Network (CAN) data bus with the Electromechanical Instrument Cluster (EMIC), the Power train Control Module (PCM), and/or the diagnostic scan tool.

The SKREEM retains in memory the ID numbers of any Sentry Key transponder that is programmed into it. A maximum of eight Sentry Key transponders can be programmed into the SKREEM. For added system security, each SKREEM is programmed with a unique Secret Key code. This code is stored in memory, sent over the CAN data bus to the PCM, and is encoded to the transponder of every Sentry Key that is programmed into the SKREEM. Therefore, the Secret Key code is a common element that is found in every component of the Sentry Key Immobilizer System (SKIS). Another security code, called a PIN, is used to gain access to the SKREEM Secured Access Mode. The Secured Access Mode is required during service to perform the SKIS initialization and Sentry Key transponder programming procedures. The SKREEM also stores the Vehicle Identification Number (VIN) in its memory, which it learns through a CAN data bus message from the PCM during SKIS initialization.

In the event that a SKREEM replacement is required, the Secret Key code can be transferred to the new SKREEM from the PCM using the diagnostic scan tool and the SKIS initialization procedure. Proper completion of the SKIS initialization will allow the existing Sentry Keys to be programmed into the new SKREEM so that new keys will not be required. In the event that the original Secret Key code cannot be recovered, SKREEM replacement will also require new Sentry Keys. The diagnostic scan tool will alert the technician during the SKIS initialization procedure if new Sentry Keys are required.

When the ignition switch is turned to the On position, the SKREEM transmits an RF signal to the transponder in the ignition key. The SKREEM then waits for an RF signal response from the transponder. If the response received identifies the key as valid, the SKREEM sends a valid key message to the PCM over the CAN data bus. If the response received identifies the key as invalid or if no response is received from the key transponder, the SKREEM sends an invalid key message to the PCM. The PCM will enable or disable engine operation based upon the status of the SKREEM messages. It is important to note that the default condition in the PCM is an invalid key; therefore, if no message is received from the SKREEM by the PCM, the engine will be disabled and the vehicle immobilized after two seconds of running.

The SKREEM also sends security indicator status messages to the EMIC over the CAN data bus to tell the EMIC how to operate the security indicator. The security indicator status message from the SKREEM tells the EMIC to turn the indicator on for about three seconds each time the ignition switch is turned to the On position as a bulb test. After completion of the bulb test, the SKREEM sends security indicator status messages to the EMIC to turn the indicator off, turn the indicator on, or to flash the indicator on and off. If the security indicator flashes or stays on solid after the bulb test, it signifies a SKIS fault. If the SKREEM detects a system malfunction and/or the SKIS has become inoperative, the security indicator will stay on solid. If the SKREEM detects an invalid key or if a key transponder-related fault exists, the security indicator will flash. If the vehicle is equipped with the Customer Learn transponder programming feature, the SKREEM will also send messages to the EMIC to flash the security indicator whenever the Customer Learn programming mode is being utilized.

The SKIS performs a self-test each time the ignition switch is turned to the On position, and will store fault information in the form of a Diagnostic Trouble Code (DTC) in SKREEM memory if a system malfunction is detected. The SKREEM can be diagnosed, and any stored DTC can be retrieved using a diagnostic scan tool.     

Certain functions and features of the Remote Key Entry system rely upon resources shared with other electronic modules in the vehicle over the CAN data bus network. For diagnosis of these electronic modules or of the data bus network, the use of a scan tool and the appropriate diagnostic information are required.


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