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Can someone explain the Sentry Key System?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=83902		 Page 1 of 1
Author:  agood1 [ Fri Jan 22, 2016 3:14 pm ]
Post subject:  Can someone explain the Sentry Key System?
Here's the deal, I have a 2005 Liberty CRD. I just bought it. Got a good deal because the battery was dead and he could not get it started. So I towed it home, and charged the battery. Now when I turn the key...the ignition powers up and all the dash lights come on, but it will not activate the starter....I noticed the red dot light next to the fuel gauge and some research says that is a problem with the Key Sentry System. More research has just been confusing...some say that if the key sentry system is not working, that the engine will start and then shut off....others say that it has the same symptom I have...which is no starter engagement,

I am able to engage the starter while bypassing the starter relay, but the engine just spins and wont fire.....Im assuming because the Key Sentry System has somehow disabled the injectors or something to stop the engine from running....

I have also checked the ignition actuator pin and it is NOT broken.


Can someone enlighten me on how this system should work?

Thanks
Author:  papaindigo [ Fri Jan 22, 2016 4:41 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
If you don't have a hard copy of the Owner's Manual (look on shelf in top of glove box) you can download a PDF version at Jeep.com by clicking on the Owners link. It has a bit of an explanation. Unrelated by read Sir Sam's NOOB guide.

I don't know all the details so others may correct or expand:
1. SKS system involves a "chipped" key (may be a simple chipped key or the more elaborate key fob with remote buttons) and
2. an antenna wire near the ignition switch
3. when a key is inserted in the switch and turned on "if" the antenna receives a proper signal (not sure whether the signal is reviewed by the ECU or body control module) the vehicle will start an run; if not the vehicle will start and die in ca. 2 seconds
4. if the SKS light is staying on there is a problem with the SKS electronics
5. turning the key turns that acuator pin which in turn activates the ignition switch on the opposite side of the steering column. If that switch is bad there will be no start - similarly if the ECU is not "happy" with battery level there will be no start. Take a look at chat at viewtopic.php?f=5&t=61233&p=678574&hilit=+brother#p678574 . If you need copies of tZac's missing images email me using the link below.
6. could be gear shift lever position sensor
Author:  ebbnflow [ Fri Jan 22, 2016 4:49 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
X2 what papa said. In my jeep if you try to start it with an unprogrammed key, it will start and run for 2-3 seconds and then turn off.
Author:  flash7210 [ Fri Jan 22, 2016 6:21 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Check the ASD fuse.
If the fuse is blown, the red dot will light, and the engine will crank but not start.
Author:  agood1 [ Fri Jan 22, 2016 6:59 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Thanks. But let me simplify. If the red sentry light is on solid what happens?
Author:  flash7210 [ Fri Jan 22, 2016 7:02 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
agood1 wrote:
Thanks. But let me simplify. If the red sentry light is on solid what happens?


Engine cranks but wont start.
Author:  agood1 [ Fri Jan 22, 2016 8:56 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
flash7210 wrote:
agood1 wrote:
Thanks. But let me simplify. If the red sentry light is on solid what happens?


Engine cranks but wont start.

Ok. I got no crank using the key. Only if I trigger the starter via the relay.
Is there a way to reset the key sentry and make the light go out.
Author:  flash7210 [ Fri Jan 22, 2016 9:07 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Check for trouble codes. Might help narrow the problem down.
Author:  agood1 [ Fri Jan 22, 2016 9:25 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
No Codes, Scanned the ECM,TCM, and BCM.

What doe ASD stand for?
Author:  Billwill [ Sat Jan 23, 2016 2:29 am ]
Post subject:  Re: Can someone explain the Sentry Key System?
agood1 wrote:
No Codes, Scanned the ECM,TCM, and BCM.

What doe ASD stand for?


Auto Shutdown Relay...in the fuse/relay box under the hood....swap it over with an identical one next to it. :wink:

The red LED being ON solid means that the ECM was happy with the chipped key code sent to it by the SKIM unit on the top of the steering column. The ECU then sends a signal to the ASD relay to energize. If the ASD relay has energized, the contact inside it sends voltage to various points...one of which is back to the ECU to acknowledge to the ECU that the ASD relay has in fact energized. If the ECU does not receive this confirmation...maybe due to a bad ASD relay or a wiring problem...then the red Led is lit solidly.

Earlier CRDs would have still allowed the starter relay to enegize and turn the engine over while the ECM would prevent the injectors from firing. Newer CRDs have the ECM energizing the ground leg of the Starter Relay coil so in this case the ECM is not happy that the ASD Relay has energized and prevents the Starter relay from energizing.

So swapping over the ASD relay may cure the problem or there may be a wiring problem. You can try removing the ASD relay and jumper pins 30 to 87 inside the socket and see if the red LED goes out and if the engine turns over and fires.

If swapping over the ASD relay does not solve your problem then you need to climb into the circuit diagrams which you can get by downloading the 2005 Jeep KJ Service Manual here:

http://www.colorado4wheel.com/manuals/Jeep/KJ
Author:  agood1 [ Sat Jan 23, 2016 12:25 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Billwill wrote:
agood1 wrote:
No Codes, Scanned the ECM,TCM, and BCM.

What doe ASD stand for?


Auto Shutdown Relay...in the fuse/relay box under the hood....swap it over with an identical one next to it. :wink:

The red LED being ON solid means that the ECM was happy with the chipped key code sent to it by the SKIM unit on the top of the steering column. The ECU then sends a signal to the ASD relay to energize. If the ASD relay has energized, the contact inside it sends voltage to various points...one of which is back to the ECU to acknowledge to the ECU that the ASD relay has in fact energized. If the ECU does not receive this confirmation...maybe due to a bad ASD relay or a wiring problem...then the red Led is lit solidly.

Earlier CRDs would have still allowed the starter relay to enegize and turn the engine over while the ECM would prevent the injectors from firing. Newer CRDs have the ECM energizing the ground leg of the Starter Relay coil so in this case the ECM is not happy that the ASD Relay has energized and prevents the Starter relay from energizing.

So swapping over the ASD relay may cure the problem or there may be a wiring problem. You can try removing the ASD relay and jumper pins 30 to 87 inside the socket and see if the red LED goes out and if the engine turns over and fires.

If swapping over the ASD relay does not solve your problem then you need to climb into the circuit diagrams which you can get by downloading the 2005 Jeep KJ Service Manual here:

http://www.colorado4wheel.com/manuals/Jeep/KJ


Well that didn't work.. I swapped the relays, and went ahead and tried the jumper method....nothing changed....red dot is still on and there is no crank with the key. I guess the only way to really diagnose the problem is to tow it to the dealer and let them use the scan tools. :(
Author:  Mike92104 [ Sat Jan 23, 2016 3:59 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
From the manual:

OPERATION
The Sentry Key REmote Entry Module (SKREEM)
contains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM 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) and the Tire Pressure Monitor (TPM)
RF receiver. (Refer to 8 - ELECTRICAL/POWER
LOCKS - DESCRIPTION) or (Refer to 22 - TIRES/
WHEELS/TIRE PRESSURE MONITORING -
DESCRIPTION). The SKREEM communicates over
the Programmable Communications Interface (PCI)
data bus with the Body Control Module (BCM), the
Electronic Vehicle Information Center (EVIC), the
Powertrain 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 PCI 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 PCI 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 PCI 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
Fig. 11 Sentry Key Remote Entry Module
1 - SKREEM
2 - BRACKET
3 - CONNECTOR RECEPTACLE
4 - ANTENNA RING
8Q - 14 VEHICLE THEFT SECURITY KJ
SENTRY KEY REMOTE ENTRY MODULE (Continued)
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 SKIS indicator status
messages to the BCM over the PCI data bus to tell
the BCM how to operate the security indicator in the
ElectroMechanical Instrument Cluster (EMIC). This
indicator status message tells the BCM 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 indicator status messages to the BCM to turn
the indicator off, turn the indicator on, or to flash the
indicator on and off. If the security indicator flashes
upon ignition On 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 BCM to flash the security indicator
and to generate a single audible chime whenever the
Customer Learn programming mode is being utilized.
(Refer to 8 - ELECTRICAL/VEHICLE THEFT SECURITY
- STANDARD PROCEDURE - SENTRY KEY
TRANSPONDER PROGRAMMING).
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. Refer to the appropriate diagnostic
information.

The solid red lights seems to indicate a problem with the sentry key system.

Before you take it to the dealer, check a few fuses in the fusebox by the steering column. 5, 13, 15, 32, 33, 36, 37, all have something to do with the Security key, or the Body control module. I had a variety of issues with my jeep. Remote locks not working, no start, no radio, and a random assortment of others. Turned out one of the BCM fuses was bad.

Good luck,
Mike
Author:  agood1 [ Sat Jan 23, 2016 5:09 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Thanks for the information. I read this in the manual and have studied the wiring diagram. I can only conclude a faulty module or a software issue. I have checked every fuse in the car and all are functioning properly.
Author:  EAB [ Sun Jan 24, 2016 10:45 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
agood1 wrote:
Thanks for the information. I read this in the manual and have studied the wiring diagram. I can only conclude a faulty module or a software issue. I have checked every fuse in the car and all are functioning properly.


Or bad key.
Author:  agood1 [ Mon Jan 25, 2016 11:18 am ]
Post subject:  Re: Can someone explain the Sentry Key System?
I have also found that none of the dome lights or cargo light has a ground. This ground is supplied by the BCM according to the wiring diagram....so either I have more than one bad door switch, or the BCM is definitely the problem.
Author:  Mike92104 [ Tue Jan 26, 2016 7:27 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Have you had the battery load tested? The ECM is VERY particular to getting good voltage from the battery. Might be worth checking. Also, I believe the BCM grounds to a grounding plate right next to it. That plate is grounded through a wire that attaches to either the drivers side motor mount, or the ground lug on the engine block. This might also be worth a look.

Mike
Author:  Turbod7 [ Thu Jan 28, 2016 9:46 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Double check fuses 13, 33 and 34 in the junction block. 13 is ignition switch output run/start and 33 is B+. Those are the only two fuses for the skim module. They are both 10amp. 34 I believe is the IOD fuse that is one power feed for the body control module. If 34 isn't labeled IOD also check that fuse, I have seen this cause skim issues on some vehicles

If you have another key that you haven't tried I would try that, although you usually get a flashing theft light with a bad key.

Good luck!
Author:  agood1 [ Thu Jan 28, 2016 10:07 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Thanks for the suggestions however I had it towed to the dealer a couple days ago. I need it fixed and done. I'll let you know what they find out.
Author:  agood1 [ Sat Apr 23, 2016 4:54 pm ]
Post subject:  Re: Can someone explain the Sentry Key System?
Turns out it was a bad ecm.
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