Turn Signal Indicator Lamp; Upshift Indicator Lamp; Wait-To-Start Lamp; Water-In-Fuel Lamp - Jeep 1997 Grand Cherokee Service Manual

ZG
DESCRIPTION AND OPERATION (Continued)
tion when the exterior lamps are lighted. The lamp is
hard-wired in the instrument cluster, and is com-
pletely controlled by the panel lamps driver circuit.
The lamp is grounded at all times and receives a
pulse-width modulated battery feed from the Body
Control Module (BCM). The instrument cluster cir-
cuitry does not perform a bulb test for this lamp.
Refer to Cluster Illumination Lamp in this group, or
to Group 8L - Lamps for more information.
SEAT BELT REMINDER LAMP
The seat belt reminder lamp gives a visual
reminder to the vehicle occupants to fasten their seat
belts. The lamp is turned on by the instrument clus-
ter circuitry for about seven seconds when the igni-
tion switch is turned to the On position. If the driver
seat belt switch is closed (seat belt is not buckled),
the Body Control Module (BCM) will also sound a
chime warning for the duration of the seat belt
reminder lamp illumination. The chime warning will
stop when the driver seat belt switch is open (seat
belt is buckled).
The seat belt reminder lamp also serves as a
backup for the airbag indicator lamp. Following the
seat belt reminder lamp seven second display func-
tion, if the instrument cluster circuitry has detected
an inoperative airbag indicator lamp circuit it will
flash the seat belt reminder lamp on and off for
twenty seconds. If the seat belt reminder lamp
flashes longer than twenty seconds, or flashes at any
time other than immediately after the initial seven
second seat belt reminder lamp display, it indicates
an airbag system fault has been detected and that
the airbag indicator lamp is inoperative.
Refer to Group 8U - Chime/Buzzer Warning Sys-
tems for more information.

TURN SIGNAL INDICATOR LAMP

The left and right turn signal indicator lamps give
an indication when the turn signal circuits are acti-
vated. These lamps are hard-wired in the instrument
cluster, and are completely controlled by the turn sig-
nal and hazard warning (multi-function) switches.
The indicator lamps are grounded at all times and
receive battery feed through the contacts of the
multi-function switch when the turn signal lever
(multi-function switch stalk) or hazard warning but-
ton are actuated to the On position. The instrument
cluster circuitry does not perform a bulb test of these
lamps. Refer to Group 8J - Turn Signal and Hazard
Warning Systems for more information.

UPSHIFT INDICATOR LAMP

Vehicles equipped with a manual transmission
have an upshift indicator lamp. The upshift indicator
lamp gives an indication when the driver should shift
INSTRUMENT PANEL SYSTEMS
to the next highest gear for the best fuel economy.
The lamp is turned on by the instrument cluster cir-
cuitry for about three seconds when the ignition
switch is turned to the On position as a bulb test.
After the bulb test, the lamp is controlled by the
instrument cluster circuitry based upon a message
received from the Powertrain Control Module (PCM)
on the Chrysler Collision Detection (CCD) data bus.
The PCM uses inputs from many sensors and its
internal programming to decide whether the engine
speed and load conditions are proper for a transmis-
sion upshift. The PCM then sends the proper mes-
sage to the instrument cluster on the CCD data bus
to turn the lamp on or off. The PCM will send a
lamp-off message three to five seconds after a
lamp-on message, if an upshift is not performed. The
lamp will then remain off until the vehicle stops
accelerating and is brought back into the range of
lamp operation, or until the transmission is shifted
into another gear. Refer to Group 14 - Fuel Systems
for more information on the PCM and the PCM
inputs.

WAIT-TO-START LAMP

Vehicles equipped with an optional diesel engine
have a wait-to-start lamp. The wait-to-start lamp
gives an indication that the conditions for easiest
starting of the diesel engine have not yet been
achieved. The lamp is turned on by the instrument
cluster circuitry for about four seconds when the
ignition switch is turned to the On position as a bulb
test. After the bulb test, the lamp is controlled by the
instrument cluster circuitry based upon a message
received from the Powertrain Control Module (PCM)
on the Chrysler Collision Detection (CCD) data bus.
The PCM uses inputs from many sensors and its
internal programming to determine whether the
proper conditions exist for easiest diesel engine start-
ing. The PCM then sends the proper message to the
instrument cluster on the CCD data bus to turn the
lamp on or off. Refer to Group 14 - Fuel Systems for
more information on the PCM and the PCM inputs.

WATER-IN-FUEL LAMP

Vehicles equipped with an optional diesel engine
have a water-in-fuel lamp. The water-in-fuel lamp
gives an indication when the water contamination in
the diesel fuel exceeds a certain level. The lamp is
turned on by the instrument cluster circuitry for
about three seconds when the ignition switch is
turned to the On position as a bulb test. After the
bulb test, the lamp is controlled by the instrument
cluster circuitry based upon a message received from
the Powertrain Control Module (PCM) on the
Chrysler Collision Detection (CCD) data bus.
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