the left and right turn sign al circu its. E ach t urn sig-
nal in dicator Ligh t Emitting Diode (LE D) is com-
pletely cont rolled by t he inst rument cluster logic
circuit, and tha t logic will allow this in dicator to
operat e whenever the instrument cluster receives a
batt ery current input on t he fu sed B(+) circuit.
Therefor e, ea ch LED can be illu min ated regardless of
the ignition switch position. Th e LE D only illu mi-
nates when it is provided a path to grou nd by the
instr umen t cluster t ransistor. Th e instrument clu st er
will tu rn on th e tur n signal indicators for the follow-
ing rea son s:
• Tu rn S i g n a l In p u t - Each time the cluster
detects a turn signal in put from the turn signa l r elay
through the closed tur n sign al switch circuitry of t he
multi-fu nction switch on the h ard wired left or right
turn sign al circu it, the requested tur n sign al lamps
and tu rn sign al indicator will be flashed on and off,
and a cont actless r elay soldered onto t he clu st er elec-
tronic cir cuit boar d will produce a clicking sound t o
emulate a conventional tur n signa l flasher. The turn
signals and the t urn sign al in dicators con tinue to
flash on and off until t he turn signal switch cir cuitry
of the multi-funct ion switch is opened, or until the
ign ition switch is turned to t he Off position, wh ich-
ever occurs first.
• Hazard Warning Input - Each time the cluster
detects a ha zar d wa rning input from the tur n signa l
rela y th rough the closed hazard warnin g swit ch cir-
cuitry of the m ult i-funct ion swit ch on the h ard wir ed
left a nd r igh t tur n sign al circuits, all of th e turn sig-
nal la mps an d both t urn signa l indicators will be
flashed on and off, and a contactless relay soldered
onto t he cluster electr onic circuit board will produce
a clickin g soun d to emu lat e a conventional ha zar d
warn ing fla sh er. Th e tu rn signa ls and the tur n signal
indicator s continu e to fla sh on an d off until the h az-
ard wa rning swit ch circuitry of the multi-fu nction
switch is opened.
An elect ronic wipers, turn signals a nd engine start
control module located wit hin the fuse block beneath
the steering column mon itors th e turn signa l cir cuits
and con trols the fla sh ra te of t he t urn sign al relay.
The in st rumen t cluster continually mon itor s th e
right and left tur n signal cir cuits to deter min e t he
pr oper turn signa l and ha zard warning indica tor
operat ion, th en flashes the proper t urn signal indica-
tors an d th e conta ctless relay on and off accordingly.
The mu lti-function switch, the turn signal relay and
the left an d r ight t urn signal circuits to the instru-
ment cluster can be diagnosed using conven tional
diagnostic tools and m ethods. For proper diagnosis of
the wipers, tur n signals and engine sta rt control
module wit hin the fu se block or th e instrumen t clu s-
ter cir cuitry that controls th e tur n signal indica tors
and the contact less rela y, a dia gnostic scan tool is
required. Refer to the appropriate diagn ost ic infor-
mation.
WAIT - TO - ST A R T INDICATO R
DESCRIPTION
A wa it-to-start indica tor is standard equipment in
all instrument clusters. Th e wait-to-start in dicator is
locat ed nea r th e lower edge of th e in st rumen t clu st er,
to the right of the multi-function indicator displa y.
The wa it-to-start in dicator consists of t he Inter na-
tional Control and Display Symbol icon for “Diesel
Preh eat” imprinted wit hin a rect angula r cut out in
the opa que layer of the instr umen t cluster overlay.
The da rk outer la yer of th e overla y prevent s the indi-
cator from being clea rly visible when it is not illumi-
nated. An am ber Light Emitting Diode (LE D) behind
the cutout in the opaque la yer of t he overla y causes
the icon to appea r silhou etted again st an am ber field
through the tr anslucent out er layer of the overla y
when the in dicator is illuminat ed from behind by the
LED, which is soldered on to th e instr ument clu st er
electronic circu it boa rd. The wait -to-star t indicator is
serviced as a un it wit h the instr umen t cluster.
OPERATION
The wa it-t o-st art indicator gives an indication to
the vehicle operator when th e diesel engine glow
plugs a re energized in their pre-h eat opera tin g m ode.
This indicator is contr olled by a transistor on th e
instr umen t clu st er circuit boa rd based u pon cluster
pr ogrammin g and electronic messa ges r eceived by
the cluster from th e Engine Contr ol Modu le (E CM)
over the Cont roller Area Network (CAN) data bus.
The wa it-t o-st art indicator Light Em itting Diode
(LED) is completely controlled by the in strument
cluster logic circu it, a nd t hat logic will only a llow
this indicator to operat e when the instrument cluster
detects tha t t he ignition switch is in the On position.
Therefor e, th e LED will always be off when th e ign i-
tion switch is in any position except On. Th e LED
only illu minates when it is pr ovided a pat h to grou nd
by the instrument cluster tr ansist or. The instrument
cluster will turn on th e wait-to-start indica tor for t he
following rea son s:
• Bulb Test - Ea ch time the ignition switch is
turned to t he On position the wa it-to-st art indica tor
is illum ina ted for abou t two seconds as a bulb test.
• Wa it-To -S ta rt La m p-On Me s s a ge - E ach tim e
the clust er receives a wait -to-star t la mp-on messa ge
from t he E CM in dicating tha t the diesel engine glow
plugs a re energized in their pre-h eat opera tin g m ode,
the wait-to-sta rt indicator will be illu minated. The
indicator rem ain s illumina ted un til t he cluster
receives a wait-to-st art la mp-off messa ge in dicating
that the pr e-heat mode of the glow plugs has been
complet ed, unt il the ECM detects that t he en gine is
running, or until t he ignition switch is tu rned to the
Off position, whichever occur s first.
8J - 28 INSTRUMENT CLUSTER VA
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