detected in the fu el filter. This indicator i s controlled
by a tra nsistor on the inst rument cluster circuit
board based upon the cluster program ming and elec-
tronic m essa ges received by t he cluster from t he
Engine Control Module (ECM) over t he Contr oller
Area Net work (CAN) da ta bus. The wa ter-in-fu el
indicator Ligh t Emitt ing Diode (LE D) is completely
controlled by the inst rument cluster logic cir cuit, and
that logic will only a llow th is indica tor to operat e
when t he in st rumen t cluster detects that the ignit ion
switch is in the On position . Ther efore, t he LED will
alwa ys be off when the ignition switch is in a ny posi-
tion except On. The LED only illuminat es wh en it is
pr ovided a pa th to groun d by t he instrument cluster
transistor. The instrument cluster will tur n on t he
water-in-fuel in dicator for th e following rea son s:
• Bulb Test - Ea ch time the ignition switch is
turned to the On posit ion the water-in -fuel in dicator
is illu minated for abou t seven seconds as a bulb test.
• Wa te r-In -F u e l La m p -On Me ss a g e - Ea ch time
the clu st er receives a water-in-fuel lamp-on message
from the ECM indicating that ther e is excessive
water in the fuel filt er with t he engine running, the
water-in-fuel indica tor will be illumina ted. The indi-
cator rema ins illu minated un til the cluster receives a
water-in-fuel lamp-off messa ge, or until the ignition
switch is tur ned to the Off posit ion, whichever occu rs
first.
The ECM continua lly m onitors the wa ter-in-fu el
sensor to det ermine whet her ther e is excessive water
in the fuel filter. The ECM then sends the proper
water-in-fuel lamp-on and lamp-off messa ges to the
instr umen t cluster. If th e water-in-fuel indicator
rema ins illum ina ted with th e engine runnin g, excess
water shou ld be drained from th e fuel filter. If the
indicator remains illum ina ted with th e engine r un-
ning after t he water has been dr ained from the fu el
filt er, it ma y in dicate that a ma lfunct ion has
occurred in the wa ter-in-fu el sen sor or cir cuits. The
ECM will store a Diagnostic Trouble Code (DTC) for
any malfun ction it det ects. For proper diagnosis of
the water-in-fuel sensor an d circuits, the ECM, the
CAN dat a bu s, or th e elect ronic message inputs t o
the instru ment cluster that control t he wa ter-in-fu el
indicator, a diagnostic scan tool is required. Refer to
the a ppr opr iate diagnostic informat ion.
8J - 30 INSTRUMENT CLUSTER VA
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