Pistonhead

Hi, I am new to the forum yet not new with Mercedes. I am currently having some issues with my car, mainly getting stuck in "Park" and won't shift to any gears but does get back to working if I turnoff the car for few minutes and start it. I've scanned it and shows a bunch of codes.

1. P179C16 (Stored) the direct select control module is faulty. The limit value for electrical voltage is not attend.

2. 475600 (Stored) No can message was received from control module 'Control module for motor electronics (ME)

644D00 (Stored) control module 'N30/4 (ESP control module) has identified undervoltage.

3. C103 (Stored) No can message was received from control module N15/5 (ESM/EWM)
1708 (Stored) Can communication with the control module 'A80 (ISM for direct select) is faulty

I had codes before but I cleared them and also disconnected both the batteries, I drove around all day no issues with shifter and transition between P, D and R was smooth but I thought of scanning again and got these codes.

Another issue is intermittent light misfire/shaking while idling and driving when the car is cold, completely goes away after 20mins when the car is at operating temperature. No enigne codes.

W212 E200 1.8 4cylinder petrol with 7 speed auto gearbox

Your valuable expertise and input is required, highly appreciated. Thank you

CaliBenzDriver

Congratulations on being on top of these troubles with your investigations. What you describe is textbook ISM acting up. It's consistent with codes.


Collectively what these codes mean is the ECU-TCU-ESP CAN stability is getting disrupted.

-- Very fat chance the tranny ISM shifter is calling for attention. It is mounted by the tranny side and needs to be SCN'ed if replaced.

It is built with solderless pins that are hardly connected through oxidized junctions. This can be made reliable with a 5mn soldering job.

The way this module is vented reminds me of the clever LED headlights vents helps them fog up .... air condensate help drive up oxidation of poor contacts.

-- Couple faults complain of undervoltage condition... Drive with the cluster showing battery sensor data to see that voltage stays in the range of 12.6V to 14.9V. Not below.


From here you can investigate further to increase diagnostic confidence in bad ISM - Clear codes then gently exercise (stress test) shifter couple times.
Fault won't return right away but you can hear and feel gear changing (P N D).
If you park on inclined driveway (garage entrance) it stresses ISM a lot more to pull the Parking stopper. Parking on the flat is a whole lot gentler for that weak shifter module.


The engine misfiring now and then may go away when the ECU CAN-Bus environment gets more fonctional. Unfortunately external disturbance can/does directly affect Bosch ECU timings . Don't worry, we'll see later if this keeps up.

What's the total mileage currently?