Th e NAG1 will defa u lt in t he cu r r en t gea r posit ion
if a DTC is det ect ed, th en a ft er a key cycle or sh ift
to pa r k th e tr a nsmission will go in to Lim p-in , wh ich
is m echa n ica l 2n d gea r. Som e DTC’s m ay a llow t h e
tr a nsmission to r esu me nor ma l oper a tion (r ecover )
if t he det ect ed pr oblem goes away. P er m a nen t
lim p-in DTC will r ecover wh en th e key i s cycled, but
if th e sa me DTC is det ect ed for t hr ee key cycles t h e
syst em will n ot r ecover a n d t he DTC must be
clea r ed fr om t h e TCM wit h t h e DRBIII sca n t ool.
On ce t h e DRBIII# is in t he Tra nsm ission por t ion
of t h e dia gn ost ic pr ogra m , it const a nt ly mon itor s
th e TCM to see if t h e syst em is in lim p-in mode. If
th e t ra n sm ission is in lim p-in mode, t h e DRBIII#
will fla sh t he red LE D.
3.2. 1 CON T R OL L ER MOD ES OF
OPERATION
P e rm a n e n t lim p-in m o d e
Wh en t he TCM det er m in es t h er e is a n on -
recover a ble con dit ion pr esent t h at will n ot a llow
pr oper t r an sm ission oper at ion , it will pla ce t h e
tr a nsmission in per m an en t lim p-in m ode. W h en t he
condit ion occu r s t he TCM will t u r n off all solen oids
as well a s th e solen oid su pply out pu t cir cuit . If th is
occur s wh ile th e veh icle is m ovin g, t h e tr an sm ission
will r em ain in t h e cu rr en t gea r u n til t he ign it ion is
tu r ned off or sh ift er is pla ced in t h e "P " posit ion .
On ce t he sh ift er ha s been pla ced in "P " the Trans-
mission will on ly a llow 2n d gea r oper at ion. If t h e
pr oblem occu r s wh ile th e veh icle is n ot m ovin g the
tr a nsmission will on ly a llow 2n d gea r oper at ion .
Te m po ra ry lim p -in m o de
Th is m ode is th e sa m e as th e per ma n en t lim p-in
mode except if t he con dit ion is n o lon ger pr esen t t he
syst em will r esu me n orm a l opera t ion . (Recovera ble
DTC)
Un d e rv o lt a g e lim p -in m o de
Wh en t he TCM det ect s t h a t syst em volt age h as
dr opped below 8.5 volt s it will disa ble volt a ge de-
penda n t dia gn ost ics a n d pla ce t h e t ra n sm ission in
th e tem por a ry lim p-in mode. Wh en t h e TCM sen ses
th a t t h e volta ge h a s r isen a bove 9.0 volt s, n orm a l
tr a nsmission oper a t ion will be resu m ed.
Hardw are Error Mode
Wh en the TCM det ect s a m ajor int er na l er r or the
tr a nsmission will be pla ced in t he per ma n ent
lim p-in mode a nd cea se all comm u nica t ion over th e
CAN bu s. On ce t he TCM ha s ent er ed t h is m ode
nor m al t r an sm ission oper a tion will not r esum e u n -
til a ll DTC’s a re clear ed fr om th e TCM.
Lo s s o f D ri v e
If t h e TCM det ects a sit u a t ion t ha t h a s r esu lt ed or
ma y r esu lt in en gin e or t r an sm ission fa ilu r e, t he
tr a nsmission will be pla ced in t h e n eu tr a l posit ion .
Im pr oper Ra tio, In pu t Sen sor Over speed, or E ngin e
Over speed DTC’s will cau se th e loss of dr ive.
Co n tro lle d Li m p -in Mo d e
Wh en a fa ilu re condit ion does n ot requ ir e t h e TCM
to sh ut down t he solen oid su pply, bu t t h e fa ilu r e is
of a degr ee wh er e t h e TCM will pla ce t h e tra n sm is-
sion in t o a pr edefin ed gea r, t h er e will be sever a l
sh ift per form a n ce issu es. Exa m ples of t h is ar e, wit h
th e t r a nsm ission slippin g t h e con t roller will at-
tem pt to place t he t r an sm ission i n to th ir d g ea r an d
ma in t a in th ir d gea r for a ll for wa r d drive condit ion s.
Anot h er exa m ple is som e of t h e CAN bus m essa ge
issu es if the TCM does n ot r eceive r equ ir ed in for-
ma t ion fr om t he En gin e Con t roller, t h en defa u lt
va lu es a r e used wh ich m a y resu lt in poor tr an sm is-
sion sh ift per for ma n ce.
3.2.2 MIL ILLUMINATION
For fa ilu r es det ect ed by t h e Tr a n sm ission Con -
tr oller t h at resu lt in the con t roller pla cing t he
tr a nsmission in t o a lim p-in m ode, except for Syst em
Over volt age an d Syst em Un dervolt a ge DTCs, t he
MIL will be illu m in a ted. Th e Tra nsm ission Con t r ol
Module will in form t h e ECM over t h e CAN bu s th a t
a failur e ha s occu r red. Th e E CM will illu min at e th e
MIL. If t h e condit ion is r em oved an d t h e fa ilu re
becom es St or ed (In ter m it t en t ), t h e Tr a n sm ission
cont r oller will st op repor t in g th a t the DTC is a ct ive
and the ECM will extinguish the MIL.
NOTE: The MIL will light when the problem is
first detected and it will not go off until the
next ignition cycle, after all problem
conditions have been checked for their
presence. This normally takes several
minutes of driving.
3.2.3 SOLENOIDS
1-2/4-5 s o le n o id - Th e 1-2/4-5 solen oid is a ct iva ted
wh en t he TCM det er m in es t ha t t he tr a n sm ission
mu st sh ift in t o or ou t of 2n d gea r or 5t h gear. Th e
solen oid is on ly a ctiva t ed du r in g th e sh ift ing of th e
tr a nsmission . Wh en t he solen oid is a ctiva t ed, h y-
dr au lic pr essu re is a pplied to th e pr oper sh ift ele-
men t s in t he tra n sm ission t o allow th e desir ed shift .
On ce t h e sh ift is com pleted, th e solen oid is t u rn ed
off.
2-3 s o le n o id - Th e 2-3 solen oid is a ct iva ted wh en
th e TCM det er min es t ha t t he t r an sm ission m u st
sh ift in t o or ou t of 3r d gea r. Th e solen oid is on ly
act iva t ed du r in g t h e sh ift ing of t he t r an sm ission .
Wh en t he solen oid is a ctiva t ed h ydra u lic pr essu re
is a pplied t o t h e pr oper sh ift elem en ts in th e tr a n s-
mission t o a llow t h e desir ed sh ift . On ce th e sh ift is
complet ed, t he solen oid is t u rn ed off.
2
GEN ERAL I N FORM AT I ON
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