received by the clu st er from the Engine Con trol Mod-
ule (ECM) over the Controller Area Network (CAN)
da ta bus. The tachometer is a n air core magnet ic
unit th at receives ba ttery current on the in st rument
cluster electronic circuit board when t he instr umen t
cluster detect s tha t th e ign ition swit ch is in t he On
position . The clu st er is programmed to move th e
gau ge needle back to the low end of t he scale after
the ignition swit ch is t urned to th e Off posit ion. The
instr umen t cluster circuitry contr ols t he ga uge nee-
dle position and provides th e following feat ures:
• Engine Speed Message - Each time the cluster
receives an engine speed message from th e E CM it
will calcula te the cor rect engine speed rea ding a nd
position th e gauge needle at that relative speed posi-
tion on the gauge scale. Th e gauge needle will con-
tinually be reposition ed at the rela tive engine speed
position on the gau ge sca le until the en gin e st ops
running, or until t he ignition switch is tu rned to the
Off position, whichever occur s first.
• Co m mu ni c a t io n E rro r - If t he cluster fails to
receive an engine speed m essa ge, it will hold t he
gau ge needle a t the last indication for about t hree
seconds, or until the ignition switch is turned t o th e
Off position, which ever occurs first. Aft er th ree sec-
onds, the gauge needle will retur n to t he left end of
the gauge scale.
The ECM contin ually monitors the cran ksha ft posi-
tion sen sor to det ermine the engine speed. The E CM
then sends the proper engine speed m essa ges to the
instr umen t cluster. F or pr oper diagnosis of t he
crankshaft position sen sor, t he ECM, t he CAN da ta
bus, or the electr onic m essa ge inputs to th e instr u-
ment cluster t hat cont rol the tachom eter, a diagnos-
tic sca n tool is r equired. Refer to th e a ppropriate
diagnostic informat ion.
TRACTION CONTROL INDICA-
TOR
DESCRIPTION
A tra ction control (ASR) indica tor is sta ndard
equipm ent on all instr umen t clusters. The tract ion
control indica tor is located near the cent er of t he
speedom eter in t he instr ument clust er. The tract ion
control indicator consists of an “!” (excla mation point)
imprinted with in a trian gular cutout 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 clear ly visible when it is not illu minated. An
amber Ligh t E mit ting Diode (LED) behind the cut out
in the opaque layer of t he overlay causes t he excla -
mation point t o appear silhouet ted again st an a mber
field through the tr anslucent outer layer of the over-
lay when the indicator is illuminated fr om behind by
the LED, which is solder ed onto the instrument clus-
ter electronic circuit boa rd. Th e tr action cont rol indi-
cator is serviced as a unit with the in st rument
cluster.
OPERATION
The tr action con trol (ASR) indica tor gives sever al
indications t o t he vehicle operat or concerning the
operat ing status of the traction con trol (ASR) system .
The tr action contr ol in dicator is controlled by a tr an-
sistor on t he instrument cluster circuit boa rd based
upon clu st er progr amming and electron ic m essages
received by th e cluster fr om the Controller Anti-lock
Brake (CAB) over t he Con troller Area Network
(CAN) data bus. The tr action cont rol indicator Light
Emitting Diode (LE D) is complet ely cont rolled by t he
instr umen t cluster logic circu it, a nd th at logic will
only allow t his indicator to oper ate when th e instru-
ment cluster detect s th at the ignition switch is in t he
On posit ion. Therefore, the LED will a lways be off
when t he ignition switch is in an y position except
On. The LED on ly illuminates when it is provided a
pa th to grou nd by the instr umen t cluster tra nsistor.
The instrument cluster will tur n on the traction con-
trol indicator for th e following rea son s:
• Bulb Test - Ea ch time the ignition switch is
turned to the On position t he tr action cont rol indica-
tor is illumina ted for about two seconds as a bulb
test.
• Tra c tio n Co n tro l (AS R ) In d ic a t o r La m p -On
Message - Each time t he clu st er receives a t raction
control in dicator lam p-on message from the CAB, the
indicator will be illuminated. This indica tor can be
flashed on and off, or illum inated solid, as dictated
by the CAB message. The indicator is illuminat ed
solid when the tr action cont rol system has been deac-
tivated; and is flashed when the tra ction control is
activat ed or wh en the driven wh eels lose tract ion
with the tra ction cont rol dea ctivated. The in dicator
rema ins flashing or illum ina ted solid until t he clus-
ter receives a lam p-off message from t he CAB, or
until the ignition switch is t urned t o t he Off position,
which ever occurs first.
The CAB continua lly m onit ors t he tra ction control
(ASR) switch and t he four wheel speed sensors to
determ ine t he correct operat ing mode for th e tra ction
control syst em. The CAB then sends the proper
lam p-on or lamp-off messages to the instrument clus-
ter. See th e own er’s manua l in t he vehicle glove box
for more in format ion on the features, use, activation
and deactiva tion of the tr action contr ol (ASR) system .
For proper diagnosis of t he tra ction cont rol system,
the CAB, the CAN data bus, or t he electr onic mes-
sa ge inputs to the instrumen t cluster th at con trol th e
traction control indica tor, a diagn ost ic scan t ool is
required. Refer to the appropriate diagn ost ic infor-
mation.
8J - 26 INSTRUMENT CLUSTER VA
To Next Page
Loading...
