Chrysler 2005 Sebring, Руководство по обслуживанию, Страница: 581 / 3204

DOWNSHIFT DELAY
DESCRIPTION
Downshift delay features have been added to
reduce the number and frequency of downshifts when
operating in hilly or mountainous country.
OPERATION
While operating, interactive speed control delays or
avoids downshifts by allowing up to nearly wide open
throttle without the TCM (on SBEC vehicles) (PCM
on NGC vehicles) scheduling a downshift. If the
interactive speed control is not engaged or the throt-
tle is manually overridden by the driver while inter-
active speed control is engaged, the downshift delay
feature is not activated.
Torque converter lock and unlock shifts are not
affected by the downshift delay feature and will occur
at the same throttle angle at a given speed regard-
less of whether interactive speed control operates or
not.
GRADE HUNTING
DESCRIPTION
All vehicles equipped with a four speed automatic
transmission have a grade hunting feature for the
2nd to 3rd gear upshift and the 3rd to Overdrive
upshift.
OPERATION
The TCM (on SBEC vehicles) (PCM on NGC vehi-
cles) identifies the powertrain loading conditions and
selects the proper gear to maintain the current vehi-
cle speed. Under moderate loading conditions the
transaxle will stay in 3rd gear until the top of the
grade is reached or the powertrain loading is
reduced.
If powertrain loading is severe, the transaxle may
shift into 2nd gear and remain there until power-
train loading is reduced, then a 2nd to 3rd gear
upshift will be scheduled. Grade hunting features
always operate regardless of whether or not the
interactive speed control is engaged.
If th e in te ra c -
tiv e s p e e d c o n tro l is n o t e n g a g e d a n d p o w e r-
tra in lo a d in g is n o t re d u c e d , th e d riv e r m a y
h a v e to c o m p le te ly lift o ff o f th e th ro ttle be fo re
a n u p s h ift w ill o c c u r
. If the driver does lift off the
throttle to induce an upshift under these conditions,
vehicle speed will reduce and the Overdrive to 3rd
and 3rd to 2nd gear downshifts will reoccur when the
throttle is reapplied. If grade hunting is repeatedly
induced by the driver, transaxle damage may result.
AUTOMATIC SPEED CONTROL OVERSPEED
REDUCTION
DESCRIPTION
Transmission control software includes an auto-
matic speed control overspeed reduction feature. This
maintains vehicle speed at the selected set point
when descending a grade.
OPERATION
The TCM (on SBEC vehicles) (PCM on NGC vehi-
cles) first senses that the speed control is set. If the
set speed is exceeded by more than 4 mph (6.5
km/hr) and the throttle is closed, the TCM (on SBEC
vehicles) (PCM on NGC vehicles) causes the trans-
axle to downshift to THIRD gear. After downshifting,
the automatic speed control resumes normal opera-
tion. To ensure that an upshift is appropriate after
the set speed is reached, the TCM (on SBEC vehi-
cles) (PCM on NGC vehicles) waits until the speed
control system opens the throttle at least 6 degrees
before upshifting to OVERDRIVE again.
If the driver applies the brakes, canceling auto-
matic speed control operation with the transaxle still
in THIRD gear, the TCM (on SBEC vehicles) (PCM
on NGC vehicles) maintains this gear until the driver
opens the throttle at least 6 degrees to avoid an inap-
propriate upshift. The upshift is also delayed for 2.5
seconds after reaching the 6 degrees throttle opening
in anticipation that the driver might open the throt-
tle enough to require THIRD gear. This will avoid
unnecessary and disturbing transmission cycling. If
the automatic speed control RESUME feature is used
after braking, the upshift is delayed until the set
speed is achieved to reduce cycling and provide bet-
ter response.
OPERATION
When speed control is activated by depressing the
ON switch, the PCM allows a set speed to be stored
in RAM for speed control. To store a set speed,
depress and release the SET switch while the vehicle
is moving at a speed between 30 and 85 mph. In
order for the speed control to engage, the brakes can-
not be applied, nor can the gear selector be indicat-
ing the transmission is in Park or Neutral (ATX) or
1st/2nd gear (MTX). The speed control can be disen-
gaged manually by:
•
Stepping on the brake pedal
•
Depressing the OFF switch
•
Depressing the CANCEL switch.
•
Depressing the clutch pedal
•
Operating in 1st or 2nd gear (autostick, if
equipped)
8P - 2 SPEED CONTROL
JR
SPEED CONTROL (Continued)