through the fuel level sense circuit. The fuel level
sensor is a potent iomet er that changes resistance
according to the fuel level. As the fuel level
decreases, th e resistance throu gh the fuel level sen -
sor increases. The instrument cluster applies a fuel
tank cha racter istic cu rve and fuel t ank reser ve va lve
setting to the fuel level sensor input, which m ust be
configured wh en the cluster is initia lized. These
characteristics determine th e algorit hm the cluster
uses to display th e fuel level da ta on the fuel gau ge
and th e con trol for t he low fuel wa rning indicator.
The fuel level sen sor and the fuel level sen se cir cuit
to t he instru ment clust er can be diagn osed using con-
vent iona l dia gnostic tools and meth ods. F or pr oper
diagnosis of the instr umen t cluster circuitr y that con-
trols th e fuel ga uge, a diagnostic scan tool is
required. Refer to the appropriate diagn ost ic infor-
mation.
LOW OI L LEV EL I N DI CAT OR
DESCRIPTION
A low oil level indicator is st andard equipm ent on
all inst rument clust ers. The low oil level indica tor is
locat ed nea r th e lower edge of th e in st rumen t clu st er,
to the left of the m ulti-funct ion in dicator display. The
low oil level in dicator consists of the Int erna tion al
Contr ol and Display Symbol icon for “Engine Oil”
imprinted within a r ectan gular cut out in the opa que
layer of the instrument cluster overlay. The dar k
outer layer of the overlay pr events t he in dicator fr om
being cl early visible when it is not illuminat ed. A red
Light Emitting Diode (LED) behin d the cut out in the
opa que layer of the overla y causes the icon to appear
silhouetted again st a r ed field th rough the translu-
cent outer layer of th e overla y wh en th e in dicator is
illuminated from behind by the LE D, which is sol-
dered on to the inst rument cluster elect ronic circuit
board. The low oil level indica tor is serviced as a unit
with t he in st rumen t cluster.
OPERATION
The low oil level indica tor gives a n indication to
the vehicle operat or when the en gine oil level is low.
This indicator is contr olled by a transistor on th e
instr umen t cluster electronic circu it board ba sed
upon clu st er progr amming and electron ic m essages
received by the clu st er from the Engine Con trol Mod-
ule (ECM) over the Controller Area Network (CAN)
da ta bu s. The low oil level in dicator Light Emitting
Diode (LED) is completely controlled by the instr u-
ment cluster logic circuit, an d t hat logic will only
allow this indicator to opera te when the inst rument
cluster detect s tha t th e ign ition swit ch is in t he On
position . Ther efore, the LED will alwa ys be off wh en
the ignition swit ch is in any position except On . The
LED only illu min ates when it is pr ovided a path t o
ground by the instru ment cluster transistor. Th e
instr umen t cluster will turn on th e low oil level indi-
cator for th e following rea son s:
• Bulb Test - Ea ch time the ignition switch is
turned to the On posit ion th e low oil level in dicator
is illum ina ted for abou t two seconds as a bulb test.
• Engine Oil Level Low Message - Once the
engine ha s been star ted, each tim e t he clust er
receives a messa ge from the ECM in dicating tha t the
engine oil level is a t or near the “Minimum ” ma rk on
the dipstick, th e low oil level indica tor is illuminat ed.
The indicator remains illuminated briefly at fir st , but
will remain illuminated for longer periods as subse-
quent messages indicate th at t he oil level h as
dr opped fur ther. Eventually, the indica tor will
rema in illuminat ed solid u ntil the en gine oil level is
correct ed, or u ntil t he ignition switch is t urned to the
Off position, whichever occur s first.
The instrument cluster also su pplemen ts the oil
level indicator by displa yin g an engine oil icon along
with alpha-num eric messages in t he mu lti-funct ion
indicator Liquid Cryst al Display (LCD) advising th e
vehicle opera tor h ow much oil is requir ed to cor rect
the engine oil level, and when the “Maximum” engine
oil level has been exceeded. See the own er’s ma nua l
in the vehicle glove box for mor e inform ation on this
featu re.
The ECM continu ally monitors th e engine oil level
and tempera ture sensor to determine t he en gine oil
level. The ECM then sen ds t he proper engine oil
level messages t o th e instr ument cluster. If the
instr umen t cluster turns on the indicator a fter th e
bulb test, even after the engine oil level is sufficient ,
it may indicate th at t he engine or the engine oilin g
system requires service. For proper diagn osis of the
engine oil level and temperature sensor, the E CM,
the CAN da ta bus, or the electronic message inputs
to t he instrument cluster t hat cont rol t he low oil
level indica tor, a diagnostic scan tool is required.
Refer to t he appropriate diagnostic informat ion.
MAINTENANCE INDICATOR
DESCRIPTION
An Act ive Service SYSTem (ASSYST) en gine oil
maintenance in dicator is optional equipmen t on all
instr umen t clu st ers. In vehicles so equipped, a sec-
ond, dedicat ed ASSYST m icroprocessor is integral to
the cluster electron ic circuit board. The ASSYST indi-
cations ar e displayed an d can be toggled wit h th e
clock in dication on the right side of th e multi-func-
tion indica tor Liquid Crystal Display (LCD) locat ed
near the lower edge of t he instr umen t cluster,
direct ly below the speedomet er. The ASSYST displays
include n umer ic values combined with severa l icons
to indicate act ual engine oil level, and reminders in
time (days) or dist ance (miles or kilometers) un til the
8J - 20 INSTRUMENT CLUSTER VA
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