Brief description of AF33-5
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Brief description of AF33-5
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The AF33-5 is an electronically-controlled, 5-speed automatic transmission with a lock-up function.
AF33-5 basically consists of 4 planetary gear sets, plate clutches, a torque converter with lock-up clutch, a hydraulic control system and an electronic control system.
The gearbox is controlled by a control module (TCM), which continuously processes information from its own sensors as well as from other control modules. On the basis of this processed information, it controls the transmission hydraulic system.
Compared with conventional hydraulically-controlled transmissions, the AF33-5 has the following advantages:
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Improved shifting performance and smoother shifting as torque is reduced when shifting takes place.
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Reduced mechanical stresses on the entire drive train due to torque limitation.
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Improved fuel economy thanks to driving programmes optimizing fuel consumption as well as lock-up in 3rd, 4th and 5th gears (V6 petrol: 4th and 5th gears only). Under certain driving conditions when a special gearchange program is active it is possible to drive in 3rd gear with lock-up instead of 4th gear without lock-up. To improve fuel economy further, the lock-up clutch is allowed to slip. This means that a difference of 50 and 200 rpm is permitted between the engine speed and the input shaft speed. This is only permitted during gentle acceleration. The engine then pulls for longer in the higher gear before changing down. The slipping lock-up is the main reason for the choice of a higher grade transmission fluid. If the temperature of the transmission fluid rises, a temperature-dependent program is automatically selected, protecting the gearbox from heat damage. Refer to
Special gearchange programs.
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The possibility of selecting different driving programs: NORMAL, SPORT and WINTER.
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Self-diagnosis and storage of diagnostic trouble codes.
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The TCM sends and receives information from other control modules in the car by means of bus communication, see
Bus communication
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Selector lever position P
Position P must only be selected when the car is stationary. The selector lever and the transmission are both locked. The engine can be started.
Selector lever position R
Position R must only be selected when the car is stationary. This position cannot be selected without lifting the selector lever detent.
Wait a moment before depressing the accelerator to give the reverse gear time to engage properly.
To protect the transmission against damage, it is not possible to engage reverse at speeds above 7 km/h forwards. This is effected by releasing brake B3 which is normally applied for reverse.
Selector lever position N
In position N the transmission is in neutral. The engine can be started. The handbrake should be applied to prevent the car moving.
To avoid excessively high engine and transmission temperatures, N should be selected when the car is at a standstill for lengthier periods.
NOTE: Never select position N while the car is moving. This could damage the clutches.
Selector lever position D
Position D is the normal driving position. After selecting this position, wait a moment before depressing the accelerator to give the gears time to engage properly. The transmission automatically shifts between gears 1 and 5. The shifting points depend on the position of the accelerator and the speed of the car.
Selector lever position 4
In this position, 5th gear is blocked. The car starts in 1st gear and then shifts automatically between gears 1 - 4.
If you shift from D to 4, the transmission will change down to 4th gear and the braking force of the engine will increase. The lever should not be moved to this position at speeds above 150 km/h.
Selector lever position 3
This position is to be preferred when driving in mountainous areas with a heavily laden car. The engine power is utilized more efficiently and the braking power is increased. The transmission shifts automatically between 1st and 3rd gears. Gears 4 and 5 are blocked. The lever should not be put in position 3 at speeds exceeding 125 km/h.
Selector lever position L
Position L should be selected to provide stronger engine braking when descending extremely steep hills and when starting with a heavy load up a very steep incline. The transmission changes between 1st and 2nd gear.
Moving the selector lever from position D to position L will result in immediate downshifting to 4th gear if the car is travelling at 175 km/h or less. Downshifting from 4th to 3rd gear takes place at 125 km/h, from 3rd to 2nd at 75 km/h, and from 2nd to 1st gear at about 35 km/h. This procedure is designed to increase road safety and protect the power train. Downshifting must not be performed manually at speeds above 150 km/h.
Towing
The following rules must be observed when towing a car that has automatic transmission:
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The car must only be towed in the forward direction (front wheels leading).
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The selector lever must be in position N.
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National regulations governing towing speeds must be observed.
The car must not be towed at speeds in excess of 50 km/h, even if the legal limit is higher. The car must not be towed further than 40-50 km. If it needs to be towed further than this, its front wheels must be raised off the ground.
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4.
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When the car is ready to be used again the transmission fluid should be checked and, if necessary, drained to the prescribed level.
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5.
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The engine cannot be started by pushing or towing the car.
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