Checking Automatic Transmission
Checking automatic transmission
Check the quality of the transmission oil
Check the quality of the transmission oil
Check the quality of the transmission oil
Note! The transmission fluid quality is extremely important for transmission function. Therefore it is imperative that this is correct.
- Ignition off.
Check the transmission oil quality. Take a sample using the dip stick.
- Replace the transmission fluid if it smells burnt
- Replace the fluid and filter if the transmission fluid contains particles
- Check if there is oil or an oil film in the expansion tank. Oil in the expansion tank indicates leakage from the transmission oil cooler which is positioned in the cooler unit.
Note! The transmission oil is red and must not be confused with black engine oil.
- If the transmission fluid is cloudy or pink, it is contaminated with coolant. In such cases the transmission must be replaced. For checking coolant in transmission oil, see: Checking for coolant in the oil, AW55-50/51SN, AW50/51 AWD, 4T65EV-GT Checking For Coolant In the Oil
When replacing the transmission, the cooler unit, including the additional cooler must be replaced if installed. Replace the hoses between the cooler and the transmission.
Other information:
- To replace the transmission fluid and filter, see Gearbox fluid, replacing Removal and Replacement.
Select an option:
1. The fluid contains water
2. The fluid smells burnt or contains particles
3. No fault detected.
1 - WATER
2 - BURNT
3 - NOFAULT
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WATER - Replacing the transmission
BURNT - Resetting the oil quality counter
NOFAULT - Checking the oil level in the transmission
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Checking the oil level in the transmission
Checking the oil level in the transmission
Check the transmission oil level
Note! The transmission fluid level is extremely important for transmission function. Therefore it is imperative that it is correct. In addition the oil level is dependent on oil temperature.
- Start the car
- Read off the oil temperature.
When checking the transmission fluid level, the temperature must be 80-90°C.
At the correct temperature, the oil level should be between "Min hot" and "Max hot".
Oil level
- Too high:Drain the transmission fluid to the correct level
- Too low:Check the transmission for leakage.
Remedy as necessary.
Other information:
- To check and adjust the oil level, see Oil level, checking Checking Oil Level.
Was the transmission fluid level correct?
Yes - OK
No - NOTOK
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OK - Test driving
NOTOK - Resetting the oil quality counter
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Test driving
- Drive the car until the transmission oil reaches normal operating temperature. When test driving the transmission should be at operating temperature, approximately 80-90°C.
Start in gear position D and accelerate using even throttle application.
Drive the car to the gearshift from 2nd up to 3rd. Be observant when the transmission shifts up. Check if the car judders, vibrates or shifts harshly during the gearshift. Repeat the shift between 2nd and 3rd gears several times.
If there are vibrations and judders when gear shifting, the line pressure solenoid STH is defective and the solenoid must be replaced.
Hint: In order for the transmission control module (TCM) to adapt the gear shifting ratios to the correct level, the same gear shifting must be repeated 5-10 times.
Other information:
- To replace solenoid STH, see Solenoid line pressure, replacing .
Did the transmission operate correctly?
Yes - No Fault Found
No - Resetting the adaptation and oil quality counter
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Test driving
Hint: Test the transmission to check that the solenoid STH corrected the fault.
- Drive the car until the transmission oil reaches normal operating temperature. When test driving the transmission should be at operating temperature, approximately 80-90°C.
Start in gear position D and accelerate using even throttle application.
Drive the car to the gearshift from 2nd up to 3rd. Be observant when the transmission shifts up. Check if the car judders, vibrates or shifts harshly during the gearshift. Repeat the shift between 2nd and 3rd gears several times.
If there are vibrations and judders when gear shifting, the line pressure solenoid STH is defective and the solenoid must be replaced.
Hint: In order for the transmission control module (TCM) to adapt the gear shifting ratios to the correct level, the same gear shifting must be repeated 5-10 times.
Is the transmission operating correctly?
Yes - FAULT FOUND
No - Replacing the transmission
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Replacing the transmission
Fault-tracing indicates a mechanical fault in the transmission. Replace the transmission.
Other information:
- To remove the transmission, see Gearbox, removing Gearbox, Removing
- To install the transmission, see Gearbox, installing Gearbox, Installing.
Select "Continue" when the fault has been remedied.
Continue - Resetting the adaptation and oil quality counter
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Resetting the adaptation and oil quality counter
Resetting the adaptation
Resetting adaptation and the counter for "Transmission oil change"
Hint: The transmission has torque controlled adaptive pressure control. Pressure control means that the transmission regulates the pressure itself during each gear shift. This avoids harsh gear shifting. Each gear shift is evaluated by the control module and stored in the memory. This allows for compensation for wear and tear in the transmission and clutch. It is important that the adaptation in the memory is reset after the transmission has been repaired. This is to ensure normal operation. The oil is replaced during repair; the "Transmission oil change" counter must be reset. If the counter is not reset when the fluid is drained and replaced, there is a risk that a diagnostic trouble code (DTC) will be stored in incorrect circumstances.
Note! This applies only if the transmission or one of the components in the transmission have been replaced.
- Ignition on.
Click on the VCT2000 symbol to reset the adaptation and counter.
Continue - DONE
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DONE - Verification
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Resetting the adaptation and oil quality counter
Resetting the adaptation, AW55-50/51SN, AW50/51 AWD, 4T65EV-GT
DONE - Test driving
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Resetting the oil quality counter
Resetting Transmission fluid change counter
Resetting Transmission fluid change counter
Hint: The transmission control module (TCM) has a counter for the oil quality. The counter counts up if the transmission is exposed to too high a load or an ambient temperature that is too high. If the counter is not reset when the oil is drained or changed, there is a risk that a diagnostic trouble code (DTC) will be stored in faulty circumstances. Therefore it is important that the "Transmission oil change" counter is reset.
Note! This applies only when the transmission fluid is changed and when the fluid is changed when repairs are carried out to the transmission temperature sensor.
- Ignition on.
Reset the counter by clicking on the VCT 2000 symbol.
Continue - DONE
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DONE - Test driving
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Verification
Verification
- Drive the car until the transmission oil reaches normal operating temperature. When test driving the transmission should be at operating temperature, approximately 80-90°C.
Start in gear position D and accelerate using even throttle application.
Drive the car to the gearshift from 2nd up to 3rd. Be observant when the transmission shifts up. Check if the car judders, vibrates or shifts harshly during the gearshift. Repeat the shift between 2nd and 3rd gears several times.
Is the transmission operating correctly?
Yes - Verification complete
No - Fault-tracing information
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - Exit Fault-Tracing
No - Attempt New Test
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Attempt New Test - Check the quality of the transmission oil
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