the button when the display is in the trip mode will reset the trip mileage. The cluster also supplies
the power for the panel illumination. Most of the information that is displayed is received over the
PCI bus from several modules.
With ignition in
9
lock
9
, the cluster will wake up and display the door ajar and odometer display
when a door is opened. The cluster will also wake up to control the panel illumination. In
9
off
9
(unlock) the PRNDL and several indicators will be functional but all gauges will not function. On
transition from
9
off
9
(unlock) to run, the cluster will perform a check of all micro-controlled
indicators, the odometer and the PRNDL for approx. 2 seconds. Other bulb checks with longer
bulb check durations will be performed based on bus messages from other modules. If the cluster
receives no PCI bus messages for (20) seconds after the transition to
9
run
9
, the cluster will display
9
no bus
9
in the odometer.
A self test can be initiated by holding down the odometer reset button and switching the ignition
from
9
lock
9
to
9
off
9
(unlock). This test will activate the gauges, turn on the indicator lights along with
the odometer and PRNDL segments.
3.10
Memory System
The memory system consists of power left front seat, power mirrors and radio presets. The
memory heated seat/mirror module (MHSMM) also includes the heated seat function. The module
is located under the left front seat and receives input from: left manual 8-way seat switch, left seat
position sensors, memory switch, both heated seat switches, both heated seat negative
temperature coefficients ((NTC’s) thermistors), PCI bus ckt, and the power mirror sensors. The
module uses these inputs to perform the following functions: position the left front seat, position
drivers memory seat and mirrors, actuate the drivers and passenger heated seat heater and send
the memory location over the PCI bus.
When a memory button is pressed (either #1 or #2) on the memory switch the MHSMM sends a
message to the BCM which in turn sends a recall message to the MHSMM and the PCI radio.
They will in turn position the left seat and both mirrors along with setting the radio presets.
3.10.1
Power Seat
The memory power seat provides the driver with 2 position settings for the left seat. Each power
seat motor is connected to the MHSMM with two circuits. Each circuit is switched between battery
and ground. By alternating the circuits the MHSMM controls the movement of the motors based
on input from the seat mounted switch.
Each motor contains a potentiometer to monitor the seat position. To monitor the position of the
motor, the MHSMM sends out a 5-volt reference on the sensor supply circuit. The sensor is
grounded back to the module on a common ground circuit. Based on the position of the sensor,
the MHSMM monitors the voltage change through the sensor on a separate signal circuit.
The MHSMM 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 seat mounted memory
switch or the RKE transmitter. When initiated, the MHSMM adjusts the four seat motors to match
the memorized seat position data.
For safety, the memory seat recall is disabled by the MHSMM when the vehicle is out of park
position. 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 MHSMM 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.
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