Jeep 1997 Grand Cherokee Service Manual page 1337

ZG
DESCRIPTION AND OPERATION (Continued)
LIFTGATE COURTESY LAMP DISABLE SWITCH
When the courtesy lamp disable switch closes, it
provides battery voltage to the Body Control Module
(BCM) on circuit M4.
AUTO HEADLAMPS
When the operator puts the headlamp switch in
the AUTO position, the auto headlamp switch closes
and connects circuit L24 from the Body Control Mod-
ule to ground. This signals the BCM to operate the
headlamps based on the ultralight sensor input. The
BCM powers the ultralight sensor on circuit L110.
Circuit L109 provides the signal from the sensor to
the BCM.
PARK LAMP SWITCH SENSE
When the operator puts the headlamp switch in
the park lamp position, the park lamp switch closes
and circuit L90 powers the parking lamps. Circuit
L90 also provides an input to the Body Control Mod-
ule (BCM). The BCM monitors the L90 circuit and
circuit 707 from the dimmer switch to determine
instrument panel lamp intensity
INSTRUMENT PANEL DIMMING
On circuit 707 from the dimmer switch in the
headlamp switch, the Body Control Module (BCM)
determines selected intensity for the instrument
panel lamps. The BCM also transmits a signal repre-
senting required lamp intensity over the CCD bus.
After receiving the signal from the CCD bus, all
other display modules update their brightness level.
IGNITION SWITCH SENSE
On circuit V23, the Body Control Module (BCM)
senses when the ignition switch is in the ACCES-
SORY or RUN position. The BCM senses when the
ignition switch is in the START or RUN position on
circuit F99.
AJAR CHIME
On models equipped with a Vehicle Information
Center (VIC), the Body Control Module (BCM)
8W - 45 BODY CONTROL MODULE
sounds an audible chime when the vehicle is moving
if one of the doors, the hood, or liftgate opens. The
BCM also signals the VIC over the CCD bus. The
VIC then displays which component is ajar.
KEY-IN IGNITION CHIME
When the key is inserted into the ignition switch,
the key-in switch closes and connects circuit G26
from the Body Control Module to ground on circuit
Z1. When the key-in switch closes, the BCM sounds
an audible fast rate chime.
SEAT BELT SWITCH
The seat belt switch closes when the seat belt is
not buckled. When closed, the switch connects circuit
G10 from the Body Control Module (BCM) to ground
on circuit Z1. If the switch is closed while the igni-
tion switch is ON, the BCM sounds an audible warn-
ing chime.
LOW OIL PRESSURE WARNING CHIME
When oil pressure drops below a calibrated level,
the Body Control Module (BCM) sounds an audible
chime to alert the operator. The BCM receives the
low oil pressure signal on the CCD bus.
ENGINE TEMPERATURE CRITICAL CHIME
When engine temperature exceeds a pre-deter-
mined temperature, the Body Control Module (BCM)
sounds an audible chime. The Powertrain Control
Module (PCM) broadcasts engine coolant tempera-
ture to the BCM on the CCD bus.
LOW FUEL WARNING LAMP ANNOUNCEMENT
CHIME
The Body Control Module (BCM) sounds an audi-
ble chime when the low fuel warning lamp illumi-
nates.
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