Toyota CAMRY 2002 Service Manual page 55

CHASSIS — U140E AND U241E AUTOMATIC TRANSAXLE
6. Shifting Control in Uphill/Downhill Traveling
General
With shifting control in uphill/downhill traveling, the ECM calculates the throttle opening angle and the
acceleration rate to determine whether the vehicle is in the uphill or downhill state. While driving uphill
on a winding road with ups and downs, the 4th upshift is restricted to ensure a smooth drive. Also, if
a brake application is detected while the ECM judges a downhill travel in 4th, the transmission automatical-
ly downshifts to 3rd in order to provide an appropriate engine brake.
In addition, while the ECM judges a downhill travel, it restricts the travel in 3rd without keeping the
brake application.
Without Control
With Control
Shifting up to the 4th speed after down
shifting to the 3rd speed is prohibited
while uphill traveling is judged.
Uphill/Downhill Judgment
The actual acceleration calculated from the speed sensor signal is compared with the reference acceleration
stored in the ECM to judge uphill or downhill traveling.
The ECM judges an uphill travel if the actual acceleration is smaller than the reference acceleration, and
restricts the 3rd to 4th upshift after a 4th to 3rd downshift has occurred. Also, the ECM judges a downhill
travel if the actual acceleration is greater than the reference acceleration, and restricts the 4th upshift while
traveling in 3rd. If a brake application is detected while traveling in 4th, it downshifts to 3rd.
Actual Acceleration < Reference Acceleration
Smaller
Uphill
Uphill
Corner
3rd 4th 3rd 4th
3rd 4th
Brake Operation
Reference acceleration
Actual acceleration
3rd 4th
Down-shift to the 3rd speed
occurs upon braking while
downhill traveling is judged.
Actual Acceleration > Reference Acceleration
Greater
Downhill
CH-143
162CH09
162CH10