Dodge Dakota 2001, Service Manual

Page: 430 / 2307

•
Bulb Test - Each time the ignition switch is
turned to the On position the coolant low indicator is
illuminated for about two seconds as a bulb test.
•
Coolant Low Lamp-On Message - Each time
the cluster receives a message from the PCM indicat-
ing the engine coolant level is low, the coolant low
indicator will be illuminated, and a single chime tone
is sounded. The indicator remains illuminated until
the cluster receives a message from the PCM indicat-
ing that the engine coolant level is not low, or until
the ignition switch is turned to the Off position,
whichever occurs first. The chime tone feature will
only repeat during the same ignition cycle if the cool-
ant low indicator is cycled off and then on again by
the appropriate lamp-off and lamp-on messages from
the PCM.
•
Actuator Test - Each time the cluster is put
through the actuator test, the indicator will be
turned on, then off again during the bulb check por-
tion of the test to confirm the functionality of the
LED and the cluster control circuitry.
The PCM continually monitors the engine coolant
level through the low coolant level switch, then sends
the proper messages to the instrument cluster. For
further diagnosis of the coolant low indicator or the
instrument cluster circuitry that controls the LED,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). For proper
diagnosis of the low coolant level switch, the PCM,
the PCI data bus, or the message inputs to the
instrument cluster that control the coolant low indi-
cator, a DRBIII
t
scan tool is required. Refer to the
appropriate diagnostic information.
CRUISE INDICATOR
DESCRIPTION
A cruise indicator is standard equipment on all
instrument clusters. However, on vehicles not
equipped with the optional speed control system, this
indicator is electronically disabled. The cruise indica-
tor consists of the word “CRUISE”, which appears in
the lower portion of the odometer/trip odometer Vac-
uum-Fluorescent Display (VFD). The VFD is part of
the cluster electronic circuit board, and is visible
through a cutout located in the lower left corner of
the cluster overlay. The dark lens of the VFD pre-
vents the indicator from being clearly visible when it
is not illuminated. The word “CRUISE” appears in
an amber color and at the same lighting level as the
odometer/trip odometer information when it is illumi-
nated by the instrument cluster electronic circuit
board. The cruise indicator is serviced as a unit with
the VFD in the instrument cluster.
OPERATION
The cruise indicator gives an indication to the vehi-
cle operator when the speed control system is turned
On, regardless of whether the speed control is
engaged. This indicator is controlled by the instru-
ment cluster circuit board based upon cluster pro-
gramming and electronic messages received by the
cluster from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus. The cruise indicator receives battery
current on the instrument cluster electronic circuit
board through the fused ignition switch output (run-
start) circuit whenever the ignition switch is in the
On or Start positions; therefore, the indicator will
always be off when the ignition switch is in any posi-
tion except On or Start. The indicator only illumi-
nates
when it is switched to ground by the
instrument cluster circuitry. The instrument cluster
will turn on the cruise indicator for the following rea-
sons:
•
Bulb Test - Each time the ignition switch is
turned to the On position the cruise indicator is illu-
minated for about two seconds as a bulb test.
•
Cruise Lamp-On Message - Each time the
cluster receives a cruise lamp-on message from the
PCM indicating the speed control system has been
turned On, the cruise indicator is illuminated. The
indicator
remains illuminated until the cluster
receives a cruise lamp-off message from the PCM or
until the ignition switch is turned to the Off position,
whichever occurs first.
•
Actuator Test - Each time the cluster is put
through the actuator test, the cruise indicator will be
turned on, then off again during the VFD portion of
the test to confirm the functionality of the VFD, and
again during the bulb check portion of the test to
confirm the functionality of the cluster control cir-
cuitry.
The PCM continually monitors the speed control
switches to determine the proper outputs to the
speed control servo. The PCM then sends the proper
cruise indicator lamp-on and lamp-off messages to
the instrument cluster. For further diagnosis of the
cruise indicator or the instrument cluster circuitry
that controls the indicator, (Refer to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the speed control
system, the PCM, the PCI data bus, or the message
inputs to the instrument cluster that control the
cruise indicator, a DRBIII
t
scan tool is required.
Refer to the appropriate diagnostic information.
AN
INSTRUMENT CLUSTER 8J - 17
COOLANT LOW INDICATOR (Continued)