Grand Cherokee 2WD V8-4.7L VIN J (2004)
sensor supply circuit. The sensor is grounded back to the module on a common ground circuit. Based on the position of the sensor, the MSM monitors
the voltage change through the sensor on a separate signal circuit.
The MSM stores the input value of each of the four seat potentiometers in memory when the system is requested. The driver can initiate memory
recall, using either the memory switch or the RKE transmitter. When initiated, the MSM adjusts the four seat motors to match the memorized seat
position data.
For safety reasons, the memory seat recall is disabled by the MSM when the vehicle is out of park position or if the seatbelt is buckled. Any
obstruction to seat movement over a 2 second delay will cause the seat to stop moving in which case a stalled motor would be detected by the MSM
which would then flag a trouble code and the corresponding seat output would be deactivated. However, if the object obstructing the seat is removed,
the seat will function normally again.
EASY EXIT SEAT (AVAILABLE WITH MEMORY SEAT)
The intent of this feature is to allow for easier entry and exit to the vehicle by moving the seat rearward a short distance when the operator turns the
vehicle off. The seat can be recalled to one of it's two set memory positions by pressing either of the memory recall buttons on the switch or the RKE
transmitters. If any seat movement is initiated, whether manual or by memory recall, after the ignition has been turned off, this will cancel any ensuing
glide to enter movement until the next ignition cycle.
This feature can be enabled/disabled by the owner through the electronic vehicle information center (EVIC) or using the DRBIII(R). When using the
DRBIII(R) it will also inform as to what state it is in. To reinstate the feature, simply repeat the process.
GUARD BANDS
The module provides guard bands which prevent the seat track from hitting the hard limits of the given seat axis during manual power seat operation.
The guard band values for each hard limit are stored in EEPROM. The guard band can be bypassed by running the seat to the end of its travel and then
releasing the switch and pressing it again. The seat will move a short distance further. Once the seat is past the guard band, it can be stored in memory,
but if recall is initiated the seat will move to the guard bands and no further.
When a seat module or seat track assembly is replaced, the DRBIII(R) must be used to perform the "Reset Guard Bands" procedure. WARNING:
The operator must be out of the seat when this procedure is being used as the seat will move to the end of it's travel in all 8 positions.
ELECTRICALLY HEATED SEATS
The heated seat feature is available with or without the memory system. The module is located under the driver's seat and is known as the heated seat
module (HSM) or the memory heated seat module (MHSM). The control switches for the heated seats are located on the instrument panel and are
wired to the body control module. The BCM then sends the message to the HSM via the PCI bus. The system offers two seat temperature settings of
approximately 96.8° F (36° C) (LO) and approximately 107.6° F (41° C) (HI).
As the temperature in the seat rises, the negative temperature coefficient (NTC) resistance decreases and the voltage reading detected by the HSM
decreases. The seat heater output is deactivated once the voltage reading reaches it's threshold for either setting, high or low.
As the temperature decreases, the voltage reading increases until the upper threshold is reached for either setting high or low. At this point the seat
heat output is activated once again and this cycle repeats itself as long as the seat heat request is on.
The thresholds for low and high settings are preprogrammed into the module memory.
The heated seat switch contain resistors pulled up to 5 volts which are processed by the body control module as the voltage readings indicating desired
heat setting high or low.
The resistance wire type heater elements inside the seat back and cushion are wired in series. This means that if an element is open there will be no
heater output to either the cushion or the seat back.
Power Sunroof
The Accessory Delay Relay in the Grand Cherokee is controlled by the Body Control Module (BCM). After the ignition has been turned off, the power
sunroof will remain operational for an additional 45 seconds. If the front doors are opened during this time, the BCM will remove power from the
sunroof.
The control of the sunroof is done through the switch to the sunroof control module. The control module is located in the roof.
Sentry Key Immobilizer System(SKIS)
The Sentry Key Immobilizer System (SKIS) is an immobilizer system designed to prevent unauthorized vehicle operation. The system consists of a
Sentry Key Immobilizer Module (SKIM), ignition key(s) equipped with a transponder chip and engine controller. When the ignition switch is turned on,
the SKIM interrogates the ignition key. If the ignition key is "Valid" the SKIM sends a PCI Bus message to the engine controller indicating the presence
of a valid ignition key. Upon receiving a "Valid" key signal the PCM/ECM will allow the engine to continue to operate.
For additional information on the SKIS, refer to the appropriate Powertrain Diagnostic information.
