Dodge Dakota 2001, Service Manual

Page: 439 / 2307

board based upon cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus. The
oil pressure gauge is an air core magnetic unit that
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (run-start) circuit whenever the igni-
tion switch is in the On or Start positions. The clus-
ter is programmed to move the gauge needle back to
the low end of the scale after the ignition switch is
turned to the Off position. The instrument cluster
circuitry controls the gauge needle position and pro-
vides the following features:
•
Engine Oil Pressure Message - The instru-
ment cluster circuitry restricts the oil pressure gauge
needle operation in order to provide readings that
are consistent with customer expectations. Each time
the cluster receives a message from the PCM indicat-
ing the engine oil pressure is between about 6.9 kPa
(1 psi) and 137.9 kPa (20 psi) for gasoline engines, or
76 kPa (11 psi) and 206 kPa (30 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 11 degrees above the low end of normal incre-
ment on the gauge scale. Each time the cluster
receives a message from the PCM indicating the
engine oil pressure is between about 517.1 kPa (75
psi) and 755 kPa (109.5 psi) for gasoline engines, or
689 kPa (100 psi) and 755 kPa (109.5 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 7.4 degrees below the high end of normal
increment on the gauge scale. When the cluster
receives messages from the PCM indicating the
engine oil pressure is between about 137.9 kPa (20
psi) and 517.1 kPa (75 psi) for gasoline engines, or
58.6 kPa (8.5 psi) and 551.6 kPa (80 psi) for diesel
engines], the gauge needle is moved to the actual
pressure position on the gauge scale.
•
Engine Oil Pressure Low Message - Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is below about 6.9
kPa (1 psi) for gasoline engines, or 76 kPa (11 psi) for
diesel engines, the gauge needle is moved to the L
(Low) graduation at the far left end of the gauge
scale, the check gauges indicator is illuminated, and
a single chime tone is generated. The gauge needle
remains at the low end of the scale and the check
gauges indicator remains illuminated until the clus-
ter receives a message from the PCM indicating that
the engine oil pressure is above about 6.9 kPa (1 psi)
for gasoline engines, or 76 kPa (11 psi) for diesel
engines, or until the ignition switch is turned to the
Off position, whichever occurs first. The cluster will
only turn the check gauges indicator lamp on in
response to an engine oil pressure low message if the
engine speed message is greater than zero.
•
Engine Oil Pressure High Message - Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is above about 755
kPa (109.5 psi) for gasoline or diesel engines, the
gauge needle is moved to the H (High) graduation at
the far right end of the gauge scale. The gauge nee-
dle remains at the high end of the scale until the
cluster receives a message from the PCM indicating
that the engine oil pressure is below about 755 kPa
(109.5 psi) for gasoline or diesel engines, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
•
Message Failure - If the cluster fails to receive
an engine oil pressure message, it will hold the
gauge needle at the last indication until a new mes-
sage is received, 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 gauge needle will be
swept to several calibration points on the gauge scale
in a prescribed sequence in order to confirm the func-
tionality of the gauge and the cluster control cir-
cuitry.
The PCM continually monitors the engine oil pres-
sure sensor to determine the engine oil pressure. The
PCM then sends the proper engine oil pressure mes-
sages to the instrument cluster. For further diagnosis
of the oil pressure gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster turns on
the check gauges indicator due to a low oil pressure
gauge reading, it may indicate that the engine or the
engine oiling system requires service. For proper
diagnosis of the engine oil pressure sensor, the PCM,
the PCI data bus, or the message inputs to the
instrument cluster that control the oil pressure
gauge, a DRBIII
t
scan tool is required. Refer to the
appropriate diagnostic information.
OVERDRIVE OFF INDICATOR
DESCRIPTION
An overdrive off indicator is standard equipment
on all instrument clusters. However, on vehicles not
equipped with the optional overdrive automatic
transmission, this indicator is electronically disabled.
The overdrive off indicator consists of the text “O/D
OFF”, which appears in the lower portion of the elec-
tronic gear selector indicator Vacuum Fluorescent
Display (VFD). The VFD is part of the cluster elec-
tronic circuit board, and is visible through a cutout
located in the lower right corner of the cluster over-
lay. The dark lens of the VFD prevents the indicator
from being clearly visible when it is not illuminated.
8J - 26 INSTRUMENT CLUSTER
AN
OIL PRESSURE GAUGE (Continued)