Dodge Ram Truck 1500-2500-3500. Manual — part 589

SENTRY KEY IMMOBILIZER SYSTEM

WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental
restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact
sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative
(ground) cable, then wait two minutes for the system capacitor to discharge before performing further diag-
nosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the
proper precautions could result in accidental airbag deployment.

The hard wired Sentry Key Immobilizer System (SKIS) components and circuits may be diagnosed and tested using
conventional diagnostic tools and methods. Refer to the appropriate wiring information. The wiring information
includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention,
connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods may not prove conclusive in the diagnosis of the Sentry Key Immobilizer
Module (SKIM), the ElectroMechanical Instrument Cluster (EMIC), the Powertrain Control Module (PCM), the Pro-
grammable Communications Interface (PCI) data bus, or the electronic message inputs used to provide the elec-
tronic features of the SKIS. The most reliable, efficient, and accurate means to diagnose the SKIM, the EMIC, the
PCM, the PCI data bus, and the electronic message inputs for the SKIS requires the use of a diagnostic scan tool.
Refer to the appropriate diagnostic information.

CONDITION

POSSIBLE CAUSES

CORRECTION

SECURITY INDICATOR FAILS
TO LIGHT DURING BULB
TEST

1. Light-Emitting Diode (LED)
faulty.

1. Perform the instrument cluster actuator
test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING - ACTUATOR TEST)..

2. Fuse faulty.

2. Check the SKIM fused B(+) fuse and the
fused ignition switch output (run-start) fuse
in the Junction Block (JB). Replace fuses, if
required.

3. Ground path faulty.

3. Check for continuity to ground at the
connector for the SKIM. Repair wiring, if
required.

4. Battery feed faulty.

4. Check for battery voltage at the
connector for the SKIM. Repair wiring, if
required.

5. Ignition feed faulty.

5. Check for battery voltage at the
connector for the SKIM with the ignition
switch in the On position. Repair wiring, if
required.

SECURITY INDICATOR
FLASHES FOLLOWING BULB
TEST

1. Invalid key in ignition switch
lock cylinder.

1. Replace the key with a known valid key.

2. Key-related fault.

2. Use a diagnostic scan tool and the
appropriate diagnostic information for further
diagnosis.

SECURITY INDICATOR
LIGHTS SOLID FOLLOWING
BULB TEST

1. SKIS system malfunction/
fault detected.

1. Use a diagnostic scan tool and the
appropriate diagnostic information for further
diagnosis.

2. SKIS system inoperative.

2. Use a diagnostic scan tool and the
appropriate diagnostic information for further
diagnosis.

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STANDARD PROCEDURE

SKIS INITIALIZATION

The Sentry Key Immobilizer System (SKIS) must be initialized following a Sentry Key Immobilizer Module (SKIM)
replacement. SKIS initialization requires the use of a diagnostic scan tool. Initialization will also require that you
have access to the unique four-digit PIN code that was assigned to the original SKIM. The PIN code must be used
to enter the Secured Access Mode in the SKIM. This PIN number may be obtained from the vehicle owner, from the
original vehicle invoice, or from the DaimlerChrysler Customer Center. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES - STANDARD PROCEDURE - PCM/SKIM PROGRAMMING).

NOTE: If a Powertrain Control Module (PCM) is replaced on a vehicle equipped with the Sentry Key Immo-
bilizer System (SKIS), the unique Secret Key data must be transferred from the Sentry Key Immobilizer Mod-
ule (SKIM) to the new PCM using the PCM replacement procedure. This procedure also requires the use of
a diagnostic scan tool and the unique four-digit PIN code to enter the Secured Access Mode in the SKIM.
Refer to the appropriate diagnostic information for the proper PCM replacement procedures.

SENTRY KEY TRANSPONDER PROGRAMMING

All Sentry Keys included with the vehicle are pre-programmed to work with the Sentry Key Immobilizer System
(SKIS) when it is shipped from the factory. The Sentry Key Immobilizer Module (SKIM) can be programmed to rec-
ognize up to a total of eight Sentry Keys. When programming a blank Sentry Key transponder, the key must first be
cut to match the ignition switch lock cylinder in the vehicle for which it will be used. Once the additional or new key
has been cut, the SKIM must be programmed to recognize it as a valid key. There are two possible methods to
program the SKIM to recognize a new or additional valid key, the Secured Access Method and the Customer Learn
Method. Following are the details of these two programming methods.

SECURED ACCESS METHOD

The Secured Access method applies to all vehicles. This method requires the use of a diagnostic scan tool. This
method will also require that you have access to the unique four-digit PIN code that was assigned to the original
SKIM. The PIN code must be used to enter the Secured Access Mode in the SKIM. This PIN number may be
obtained from the vehicle owner, from the original vehicle invoice, or from the DaimlerChrysler Customer Center.
Refer to the appropriate diagnostic information for the proper Secured Access method programming procedures.

CUSTOMER LEARN METHOD

NOTE: The Customer Learn feature is only available on domestic vehicles, or those vehicles which have a
U.S. country code designator. This programming method also requires access to at least two valid Sentry
Keys. If two valid Sentry Keys are not available, or if the vehicle does not have a U.S. country code des-
ignator, the Secured Access Method MUST be used to program new or additional valid keys to the SKIM.

The Customer Learn programming method procedures are as follows:

1. Obtain the blank Sentry Key(s) that are to be programmed as valid keys for the vehicle. Cut the blank key(s) to

match the ignition switch lock cylinder mechanical key codes.

2. Insert one of the two valid Sentry Keys into the ignition switch and turn the ignition switch to the On position.

3. After the ignition switch has been in the On position for longer than three seconds, but no more than fifteen

seconds, cycle the ignition switch back to the Off position. Replace the first valid Sentry Key in the ignition switch
lock cylinder with the second valid Sentry Key and turn the ignition switch back to the On position. The second
valid Sentry Key must be inserted in the lock cylinder within fifteen seconds of removing the first valid key.

4. About ten seconds after the completion of Step 3, the security indicator in the instrument cluster will start to flash

to indicate that the system has entered the Customer Learn programming mode.

5. Within sixty seconds of entering the Customer Learn programming mode, turn the ignition switch to the Off posi-

tion, replace the valid Sentry Key with a blank Sentry Key transponder, and turn the ignition switch back to the
On position.

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6. About ten seconds after the completion of Step 5, the security indicator will stop flashing, stay on solid for three

seconds, then turn off to indicate that the blank Sentry Key has been successfully programmed. The SKIS will
immediately exit the Customer Learn programming mode. After the ignition is cycled the vehicle may be started
using the newly programmed valid Sentry Key.

Each of these steps must be repeated and completed in their entirety for each additional Sentry Key that is to be
programmed. If the above steps are not completed in the given sequence, or within the allotted time, the SKIM will
exit the Customer Learn programming mode and the programming will be unsuccessful. The SKIM will also auto-
matically exit the Customer Learn programming mode if it sees a non-blank Sentry Key transponder when it should
see a blank, if it has already programmed eight (8) valid Sentry Keys, or if the ignition switch is turned to the Off
position for more than about fifty seconds.

NOTE: If an attempt is made to start the vehicle while in the Customer Learn mode (security indicator flash-
ing), the SKIS will respond as though the vehicle were being started with an invalid key. In other words, the
engine will stall after about two seconds of operation. No faults will be set.

NOTE: Once a Sentry Key has been programmed as a valid key to a vehicle, it cannot be programmed as a
valid key for use on any other vehicle.

TRANSPONDER KEY

DESCRIPTION

Each ignition key (4) used in the Sentry Key Immobi-
lizer System (SKIS) has an integral transponder chip
(2) concealed beneath the molded rubber cap (1),
where it is secured within a plastic mount in the head
(3) of the metal key. In addition to having to be cut to
match the mechanical coding of the ignition lock cylin-
der, each new Sentry Key has a unique transponder
identification code that is permanently programmed
into it by the manufacturer, and which must be pro-
grammed into the Sentry Key Immobilizer Module
(SKIM) to be recognized as a valid key. The Sentry
Key transponder cannot be adjusted or repaired. If
faulty or damaged, the entire key and transponder unit
must be replaced.

OPERATION

When the ignition switch is turned to the On position, the Sentry Key Immobilizer Module (SKIM) communicates
through its antenna with the Sentry Key transponder using a Radio Frequency (RF) signal. The SKIM then listens
for a RF response from the transponder through the same antenna. The Sentry Key transponder chip is within the
range of the SKIM transceiver antenna ring when it is inserted into the ignition lock cylinder. The SKIM determines
whether a valid key is present in the ignition lock cylinder based upon the response from the transponder. If a valid
key is detected, that fact is communicated by the SKIM to the Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus, and the PCM allows the engine to continue running. If the PCM
receives an invalid key message, or receives no message from the SKIM over the PCI data bus, the engine will be
disabled after about two seconds of operation. The ElectroMechanical Instrument Cluster (EMIC) will also respond
to the invalid key message on the PCI data bus by flashing the security indicator on and off.

Each Sentry Key has a unique transponder identification code permanently programmed into it by the manufacturer.
Likewise, the SKIM has a unique Secret Key code programmed into it by the manufacturer. When a Sentry Key is
programmed into the memory of the SKIM, the SKIM stores the transponder identification code from the Sentry Key,
and the Sentry Key learns the Secret Key code from the SKIM. Once the Sentry Key learns the Secret Key code of

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the SKIM, it is permanently stored in the memory of the transponder. Therefore, once a Sentry Key has been pro-
grammed to a particular vehicle, it cannot be used on any other vehicle. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY - STANDARD PROCEDURE - TRANSPONDER PROGRAMMING).

The SKIS performs a self-test each time the ignition switch is turned to the On position, and will store key-related
fault information in the form of Diagnostic Trouble Code (DTC) in SKIM memory if a Sentry Key transponder prob-
lem is detected. The Sentry Key transponder chip can be diagnosed, and any stored DTC can be retrieved using a
diagnostic scan tool. Refer to the appropriate diagnostic information.

SWITCH-DOOR KEY POSITION

DESCRIPTION

Vehicles that are equipped with the optional Vehicle
Theft Security System (VTSS) have a door cylinder
lock switch (1) secured to the back of the key lock cyl-
inder inside the driver side front door. The door cylin-
der lock switch is a resistor multiplexed momentary
switch that is hard wired in series between ground and
the cylinder lock switch mux circuit input to the Elec-
troMechanical Instrument Cluster (EMIC) through a
pigtail wire (2) connected to the left front door wire
harness. The door cylinder lock switch is driven by the
key lock cylinder and contains two internal resistors.
One resistor value is used for the Lock position, and
one for the Unlock position.

The door cylinder lock switch cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced.

OPERATION

The door cylinder lock switch is actuated by the key lock cylinder when the key is inserted in the lock cylinder and
turned to the lock or unlock positions. The door cylinder lock switch closes a circuit between ground and the cylinder
lock switch mux circuit through one of two internal resistors for the ElectroMechanical Instrument Cluster (EMIC)
when the driver side front door key lock cylinder is in the Lock, or Unlock positions. The EMIC reads the switch
status through an internal pull-up, then uses this information as an input for the Vehicle Theft Security System
(VTSS) operation, as well as for control of a central locking feature for the power lock system.

The door cylinder lock switch and circuit may be diagnosed using conventional diagnostic tools and methods. Refer
to the appropriate wiring information. However, conventional diagnostic methods may not prove conclusive in the
diagnosis of the EMIC or its responses to the cylinder lock switch inputs. The most reliable, efficient, and accurate
means to diagnose the door cylinder lock switch, the EMIC, and both the hard wired and electronic message inputs
and outputs affected by the door cylinder lock switch inputs requires the use of a diagnostic scan tool. Refer to the
appropriate diagnostic information.

DIAGNOSIS AND TESTING

DOOR CYLINDER LOCK SWITCH

1. Disconnect and isolate the battery negative cable.

2. Disconnect the door cylinder lock switch pigtail wire connector from the door wire harness connector.

3. Using an ohmmeter, perform the resistance tests between the two pins in the door cylinder lock switch pigtail

wire connector. Actuate the switch by rotating the key in the door lock cylinder to test for the proper resistance
values in each of the three switch positions, as shown in the Door Cylinder Lock Switch Tests table.

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