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9-2-2-obshhie-svedeniya-o-diagnostike-neispravnostejj.html
9.2.2. General information about diagnostics of malfunctions
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Refusals of automatic transmissions can be caused by five main reasons: inefficient operation of the engine, violation of adjustments, problems with hydraulics, mechanical malfunctions or failures of the microprocessor or an alarm network. Diagnostics of these malfunctions always should begin with check of the reasons most simply subject to correction: level and condition of transmission liquid (Head Routine maintenance of the car), adjustment of drafts of the selector and butterfly valve drive. Then it is necessary to make road check for the purpose of definition of changes in AT work after the made corrections and need of further researches. If the problem is not eliminated, further diagnostics should be made by dealer office of service of the BMW company or a specialized workshop of car-care center. For information on possible malfunctions of AT address to the Section Diagnostics of malfunctions of automatic transmission at the end of this Chapter. |
Preliminary checks
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- Make on the car a short trip to warm up AT to normal working temperature.
- Check level of transmission liquid as Routine maintenance of the car is described in Head:
- If liquid level too low, make having added to the level designated by labels on measuring щупе, then make external examination of transmission on identification of signs of leaks.
- If level of liquid is unusually high, merge surplus, then check the merged liquid on cooler existence in it. Presence at transmission liquid of a cooler of the engine speaks about violation of tightness of internal walls of the radiator separating a cooler from transmission liquid (see. Head cooling System).
- If liquid is made foam, empty transmission and fill it with fresh liquid, then check, whether is not present in the merged liquid of a cooler.
- Check a liquid condition on measuring щупе. Normal color of transmission liquid - dark red. If it brown, or has a "burned" smell, merge it and fill transmission by fresh liquid. If liquid in bad condition, can indicate it or absence of regular leaving, or on internal violations in transmission work.
- Check idling turns.
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If it is obvious that the engine is faulty, do not perform preliminary checks transmission works before malfunction correction. |
- Check freedom of a course of a cable of a drive of a butterfly valve in a mode kik-Down. If necessary adjust it (see. Section Adjustment of a drive of the lever of the selector).
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The cable of a drive of a butterfly valve can normally function at the disconnected and cold engine, but to create problems after its warming up. Therefore checks of a cable make both at cold, and at the heated-up engine. |
- Check a condition of draft of management of the selector (see. Section Check of work and replacement of the switch of permission of the start/switch of fires of a backing). Make sure that it is correctly adjusted and works smoothly.
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Diagnostics of leakages of liquid
In most cases leakages of liquid are easy for finding by external survey. Repair usually consists in epiploon or laying replacement. If at external survey it is not possible to reveal leak, can help offered below action.
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- Define a liquid grade. Make sure that transmission liquid, instead of impellent oil and not brake liquid (transmission liquid has dark red color) flows away.
- Try to reveal a leak source. Make on the car a short trip, then park it over a big leaf of a pure cardboard or the newspaper. In few minutes you can reveal leak, having defined a place on a cardboard where liquid drips.
- Make careful external survey of a site of transmission suspected of leakage and area round it. Special attention give to joints of interfaced surfaces of laying. For survey of remote sites it is useful to use a pocket mirror.
- If the source of leak does not manage to be found, carefully wash out a suspected site solvent, then dry it.
- During car movement the air stream can blow off following liquid or oil on other components, complicating definition of a source of leak. After cleaning of a suspected site or make a trip on the car on small speed (to minimize an air stream), or let's to it get warm to working temperature, without moving a little (in this case completely cock the parking brake). Banish the engine on different speeds and several times carry out the transmission selector through all provisions. After that again examine a suspected component.
- After identification of a source of leak for competent its elimination it is necessary to define the leak reason. If to replace laying, having left bent a landing flange, leak will not stop. The bent flange it is necessary отрихтовать.
- Before trying to eliminate leak, make sure of performance listed below conditions, differently she can repeat.
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Some from listed below conditions cannot be executed without application extremely specialized tools and due qualification of performers. It is necessary to leave such problems to specialists of dealer office of BMW or experts in transmissions from a car-care center workshop. |
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Leaks through laying
Regularly check a condition of the pallet of a case of transmission. Check existence of all bolts and reliability of their tightening, a condition of the pallet (dents in the pallet can lead to damage of the case of the valve inside).
If pallet laying proceeds, too high level of liquid, obstruction сапуна, pulling of bolts of the pallet, a bend of a flange of the pallet, damage of a sealing surface of a case of transmission or damage of the laying can be the reasons. If for consolidation between the pallet and a case of transmission hermetic is used, it is possible that hermetic not that grade is applied. Leak can occur even because of existence of cracks or porosity in case molding.
Leaks through an epiploon
Too high level or pressure of liquid, obstruction ventilating сапуна, damage of walls of a nest of an epiploon, damage or the wrong installation of the epiploon, damage of a surface of a site of a shaft passing through an epiploon or weakening of fastening of the bearing, causing excessive degree of freedom of a shaft can be the reasons of leaks through an epiploon.
Make sure that the nut of a tube measuring щупа is strong tightened. Regularly check on existence of leaks a site round a gear wheel of a speedometer or the sensor of speed. At detection of transmission liquid check, whether the sealing ring of round section is damaged.
Leakages of a case
If leaks in the case are found, it indicates porosity existence in its molding which it is necessary to eliminate, or to replace a case.
Check reliability of fastening and a condition of shtutserny connections of hoses of a cooler.
Liquid follows through ventilating or jellied tubes
It is a sign of overflow of transmission, hit in it of a cooler, the wrong installation measuring щупа, obstruction ventilating сапуна or openings plum.
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