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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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1999 CLK 320 Transmission Problem

Customer Question

I have a 2001 CLK 320 automatic. Twice I have experienced being at a stop light and ready to take off and the car seems to be stuck in a high gear while in D. The car will not down shift or upshift. I park the car and let it sit in park for a minute then its back to normal. However today I was pulling out of a parking lot and the car seemed to jerk as I took off and seemed to be in a higher gear. While driving I put the car in Neutral then back to Drive but seemed the gearbox did not engage. The engine was turning but not action from tranny. Coasted to a parking spot put the car in Park waited a few seconds put back in Drive mode and it ran fine. Now not sure if tranny fluid is low because there is no dip stick.
Submitted: 8 years ago.
Category: Mercedes
Expert:  Stan replied 8 years ago.


The dipstick is intended for the workshop to check the oil level because there is a special sequence how the tranny fluid is checked. I can provide you with the order number of the dipstick and the instructions if you require them. First of all, the oil leve should be checked and replaced. When the oil change is done, experienced mechanic can tell if tranny is mechanically in order or not. According to the syptoms, it might be that the input and output shaft longditutual play is too big, so it must be checked without the removal of the tranny. There is a shim behind the propshaft flange which can solve the problem without dismatling tranny.

Another cause for bad shifting quality can be the engine's mass airflow (MAF) sensor.



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Customer: replied 8 years ago.
That is a respectable answer. Payment on the way. I also called dealer who advised fluid change is $240 for complete flush of coolant and trans fluid I described the issue to them as well and their response was diagnostics would be $96. I have obd2 scanner but not sure if them scanning will make any difference.
Expert:  Stan replied 8 years ago.

I am afraid that generic scanner will have limited access to the transmission control unit. But it is worth the try. Also the trans fluid should be checked for coolant traces if the tranny radiator is integrated into coolant radiator. If the tranny radiator is separate, this test is not needed.

Thanks for the accept and best regards,



Customer: replied 8 years ago.
I am being told it's the transmission ECM. Does this sound right?
Expert:  Stan replied 8 years ago.

Theoretically it might be. I would still check the shim behind the propshaft output flange. It is not so often that there is absolutely no connection in D. The shim is very cheap, and nothing hard to replace it. Ask the workshop if they are willing to take the control unit back if it is not the cause. Sometimes the gasket at the transmssion starts to leak and the tranny oil gets into tranny ECU by wires. Very often in such cases, the cleaning of the ECU will solve its malfunction. Of course the gaskets at the tranny connector must be replaced first in such case as well. There are many things to be checked before throwing parts at the problem.


Let me know what has been done so far. Oil change? Any swarf present? Any coolant traces in the tranny oil if radiators are integrated? What are the fault codes in tranny CU? Any faults in Engine CU?




Customer: replied 8 years ago.
Hey took it to shop and mechanic found vaccum line off at airmass sensor .... Car runs great now!!!!
Expert:  Stan replied 8 years ago.
Glad to hear that the car runs fine now. It is always good to start from the basics)) I hope that my input was useful to you and your mechanic, and you are satisfied with using JustAnswer.
Best Regards,

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