- a) poor dynamic characteristics of the engine,
- b) incorrect adjustment,
- c) hydraulic faults,
- d) mechanical faults,
- d) failures in the computer or its sensor network.
In any case, diagnostics of these problems should begin with easy-to-perform actions: checking the level and condition of the transmission fluid (see chapter 1), shift linkage adjustment, and throttle linkage adjustment. Then perform a road test to determine if the problem is corrected or if further diagnosis is required. If the problem persists after performing the preliminary checks and corrective actions, take the vehicle to your dealer's service department or a qualified service station for further diagnosis. For information on transmission malfunction symptoms, refer to paragraph "Troubleshooting" at the beginning of this Guide.
Preliminary checks
1. Drive the vehicle to warm up the transmission to normal operating temperature.
2. Check the transmission fluid level as described in chapter 1:
- a) If the transmission fluid level is too low, add enough fluid to bring the level to the specified zone on the dipstick, then check for external leaks (see below).
- b) If the transmission fluid level is too high, drain the excess and then check the drained fluid for coolant contamination. The presence of engine coolant in the transmission fluid in an automatic transmission indicates damage to the internal radiator baffle that separates the coolant from the transmission fluid (see chapter 3).
- c) If the fluid foams, drain and refill the transmission, then check for coolant in the transmission fluid or if the transmission fluid level is above the specified level.
3. Check the engine idle speed.
Note: If the engine is not running properly, do not continue with the preliminary checks until the problem has been corrected and the engine is running normally.
4. On early models, check the accelerator cable adjustment. Adjust it if necessary (see chapter 4).
5. Inspect the gear shift cable (see paragraph 3). Make sure it is adjusted properly and the lever drive operates smoothly.
Transmission Fluid Leak Diagnosis
6. Most transmission fluid leaks can be easily identified by visual inspection. Typically, the repair involves replacing the seal or gasket. If the leak is difficult to locate, the following procedure may help.
7. Determine what kind of fluid it is. Make sure it is transmission fluid and not engine oil or brake fluid (transmission fluid, has a dark red color).
8. Try to pinpoint the exact location of the leak. Drive your car for a few miles, then park it over a large piece of cardboard. After a minute or two, you should be able to locate the leak by looking for where the fluid is dripping onto the cardboard.
9. Carefully inspect the suspected component and the area immediately around it. Pay particular attention to the mating surfaces, the joints of which are sealed with gaskets. A mirror is often helpful when detecting leaks in hard-to-reach areas.
10. If you still cannot locate the leak, thoroughly clean the suspected area with a degreaser or solvent and then dry it.
11. Drive the vehicle for several kilometers at normal engine operating temperature, varying the driving speed. After the trip, visually inspect the suspected element again.
12. Once the leak has been located, the cause of the problem must be determined before repairs can be started. If the gasket is replaced but the sealing flange remains deformed, a new gasket will not stop the leak. The deformed flange must be straightened.
13. Before attempting to repair a leak, make sure that the following problem conditions are not present. Otherwise, they may cause another leak to occur.
Note: Some of the following conditions cannot be corrected without the appropriate special tools and practical experience. To correct such problems, contact the dealer service department or a qualified service station.
Leaks through gaskets
14. The pan should be checked periodically. Check the bolts for tightness. Make sure all the bolts are in place, the gasket is in good condition, and the pan is not deformed (dents in the oil pan may indicate damage to the valve block located in it).
15. If the oil pan gasket is leaking, the cause may be too high a fluid level or pressure, a clogged vent, too tight oil pan bolts, a deformed sealing flange, damage to the sealing surface of the transmission case, damage to the gasket, or cracks in the transmission case casting or porosity of the case. If a sealant was used instead of a gasket as a seal between the oil pan and the transmission case, it may have been incorrectly selected.
Leaks through seals
16. If the transmission seal is leaking, the cause may be too high a fluid level or pressure, a blocked vent hole, damage to the seal bore, damage to or improper installation of the seal itself, damage to the shaft surface that mates with the seal, or bearing play that may cause excessive shaft movement.
17. Make sure the dipstick tube seal is in good condition and the tube is positioned correctly. Periodically check the area around the speedometer drive gear or sensor for leaks. If fluid is evident, check the O-ring for damage.
Crankcase leaks
18. If it appears that the crankcase itself is leaking, then the casting has a porous structure and the crankcase should be repaired or replaced.
19. Make sure the hose fittings on the heat exchanger are tight and in good condition.
Leak through vent or filler line
20. If this condition occurs, the transmission is overfilled, there is coolant in the transmission fluid, the crankcase is porous, the wrong dipstick is being used, the vent or drain holes are clogged.