Vehicle: All Technical Service Bulletins
A/T Torque Converter Lock Up Concerns
Friction power of torque converter lockup clutch is too high (FC 2783) or actuation of torque converter lockup clutch not possible
(FC 0741)
Topic number L127.20P055758
Version 1
Design group 27.20 Torque converter
Date 04122013
Validity Vehicles with NAG2FE+ (7GTRONIC PLUS) and
OM642LS or M278 in combination with EHS 212 270 00
06, 212 270 01 06, 231 270 05 60
Reason for change
Complaint:
FC 2783 (Friction power of torque converter lockup clutch is too high) or FC 0741 (Actuation of torque converter lockup clutch not
possible) stored in transmission control unit. One possible additional customer complaint could be "poor acceleration" e.g. due to
torque reduction.
This can affect all NAG2FE+ (7GTRONIC PLUS) vehicles with engines OM642LS and M278 in the production period from
04/2011 to 02/2012 and with more than 6,000 mi. The two fault codes can also occur in combination with rpm sensor faults. The
rpm sensor fault is not connected with this complaint.
Cause:
Increased wear of torque converter bearing bushing.
The cause of this may be an excessively rough microsurface of the input shaft journal.
Affected transmissions: NAT2 transmissions from ID 03.318.709 to ID 03.979.899 or NAT2 transmissions from ID 07.019.944 to
ID 07.247.699
Remedy:
Disassemble the transmission and the torque converter and then polish the transmission input shaft with a 15 micro volt
microfinishing film as described in the attached instructions (use the finishing film/strip once only). The finishing film/polishing
strip can be ordered from the GLC.
In addition the torque converter must be replaced.
After replacing the torque converter, the converter adaptation data must be reset as follows:
Access Xentry: VGS Fully integrated transmission control (Y3/8n4) > Teachin processes > Reset of adaptation values >
Torque converter > Confirm torque converter replacement with Yes > Confirm reset of adaptation data with Yes
Access DAS: Electronic transmission control (722.9 7GTRONIC) > Transmission adaptation > Reset of adaptation data (torque
converter lockup clutch) > Confirm torque converter replacement with Yes > Confirm reset of adaptation data with Yes
