pr ocedures, fu rther details on wire ha rness rou tin g
and r etention, a s well as pin-out and location views
for t he va rious wire ha rness connectors, splices and
grounds.
The EMIC modules for t his model ar e serviced on ly
as complet e units. The EMIC m odu le cannot be
adju st ed or repa ired. If a gauge, a n LED indicator,
the multi-fu ction indicator LCD unit , a n electron ic
tone gen erat or, the electronic circu it board, th e cir-
cuit board h ardwa re, the cluster overlay, the cluster
housin g, the cluster hood, the cluster len s, or th e
cluster rea r cover a re damaged or faulty, the entire
EMIC modu le mu st be replaced.
OPERATION
The ElectroMechanical Instr umen t Cluster (EMIC)
is design ed to allow t he vehicle opera tor to monitor
the condition s of ma ny of the vehicle components and
operat ing syst ems. The gauges, meters and indica tors
in t he EMIC provide valuable infor mation a bout t he
powertr ain , fuel a nd emission s system s, coolin g sys-
tem, lighting system s, sa fety system s a nd man y
other conven ience item s. The EMIC is insta lled in
the in strument panel so that all of these monitors
can be ea sily viewed by t he vehicle operator when
dr iving, wh ile still allowing relative ea se of access for
service. The m icroprocessor-based EMIC h ardware
and software uses various in pu ts to control the
gau ges and indica tors visible on the fa ce of the clus-
ter. Som e of t hese input s are h ard wired, bu t ma ny
are in the form of electr onic messages that a re trans-
mitted by other elect ronic modules over t he Contr ol-
ler Area Networ k (CAN) dat a bu s n etwork. (Refer t o
8 - ELECTRICAL/ELE CTRONIC CONTROL MOD-
ULE S/COMMUNICATION - OPERATION).
The EMIC microprocessor smooths the input dat a
using algorithms to provide gauge rea dings that a re
accurate, stable an d responsive t o operatin g con di-
tions. These algorithms are designed t o provide
gau ge rea dings du ring normal operation that are con-
sistent with customer expecta tion s. However, wh en
abnor mal con ditions exist such as high coolant tem-
perat ure, th e algorit hm can dr ive the gau ge point er
to an extreme position and the m icroprocessor can
sou nd a chime through th e on-board audible t one
generat or to provide distin ct visual and au dible indi-
cations of a problem to the vehicle opera tor. The
instr umen t cluster circu itry also provides audible
turn signal an d ha zar d warnin g support by emulat-
ing the “ticking” sound associa ted with a conven-
tional electro-mech anical flasher usin g a contactless
rela y. Th e relay will also provide an in dication of a
turn sign al failure by sounding at double the usua l
frequen cy. Each audible warnin g is pr ovided to the
vehicle operat or to supplem ent a visual in dication.
The EMIC circuitry oper ates on batt ery curr ent
received t hrough a non -switched fused B(+) circu it,
and on a fused ignition switch output circuit. The
EMIC circu itry is groun ded th rough a groun d cir cuit
and take out of the fra me wir e harness with an eye-
let ter min al connector th at is secured to a stu d by a
nut at a groun d l oca tion on th e dash panel just for-
ward of the in st rument cluster. Sepa rate swit ched
ground input s from t he key-in ignition switch and
the fr ont door j a mb switches provide wa ke-up signals
to the EMIC circuitry. This arrangemen t allows th e
EMIC to provide som e featu res regardless of th e igni-
tion switch posit ion, wh ile ot her fea tures will oper ate
only wit h the ignition switch in the On position.
Proper diagn osis an d t estin g of the EMIC, th e
CAN da ta bus, th e dat a bus electronic message
input s t o a nd output s fr om the EMIC, a s well as the
retr ieva l or erasure of a Diagnostic Trouble Code
(DTC) r equires the use of a diagnostic scan tool.
Refer to th e appr opr iat e diagn ost ic in formation. See
the owner ’s manual in the vehicle glove box for m ore
information on the features, use and operation of t he
EMIC.
GAUGES
All ga uges receive batt ery cur rent throu gh the
EMIC circu itry only when the instr umen t clust er
detects the ignition swit ch is in the On position . With
the ignition switch in the Off position , ba ttery cur-
rent is not su pplied t o any gauges an d the EMIC cir-
cuitry is pr ogra mmed to move all of the gauge
needles ba ck to the low end of their r espective sca les.
Therefor e, th e ga uges do n ot accur ately indica te a ny
vehicle condition unless t he ignit ion switch is in the
On position.
All of th e EMIC gauges are air cor e magnet ic
units. Two fixed electromagnet ic coils are loca ted
with in each ga uge. These coils are wr apped at right
angles to each oth er arou nd a mova ble permanent
magnet. Th e movable ma gnet is suspended within
the coils on one end of a pivot shaft , while the ga uge
needle is attach ed to the ot her end of the shaft . On e
of th e coils h as a fixed curren t flowing th rough it to
mainta in a const ant magnetic field stren gth. Cur rent
flow t hrough th e second coil changes, wh ich ca uses
changes in its m agnetic field strength. The cur rent
flowing t hrough the second coil i s cha nged by th e
EMIC circu itry in response to messages received over
the CAN da ta bus. The ga uge needle moves a s t he
mova ble perm anen t m agnet aligns it self to the
changing ma gnet ic fields cr eated around it by the
electromagnet s.
Proper diagnosis and testing of the gau ges, t he
CAN da ta bu s and the elect ronic da ta bu s message
input s to th e E MIC th at con trol ea ch ga uge requir e
the use of a dia gnostic scan tool. Refer to the appro-
pr iate diagn ost ic information. Specific oper ation
details for each gau ge may be found elsewhere in
this service in forma tion.
VA INSTRUMENT CLUSTER 8J - 5
To Next Page
Loading...
