A/T Controls - Delayed 'D' Or 'R' Engagement
37 Sporadically no drive in D or R immediately after engine start37 10 04
2020491/2
May 17, 2010
Supersedes Technical Service Bulletin Group 37 number 09-05 dated July 7, 2009 for reasons listed below.
Affected Vehicles
Condition
After changing gear, the vehicle doesn't pull away in D or R. The engine hardly responds to the accelerator and runs only at idle speed. Despite operating the accelerator, there is negligible change to the engine RPM. The power transmission starts 2 to 5 seconds after selecting the gear, sometimes with a harsh engagement.
After switching the ignition off and on, the power transmission is normal again.
Technical Background
If the gear lever is moved during or immediately after the automatic engine start, a function of the gearbox is activated. This triggers programming in the control unit, which, depending on the temperature of engine, delays power transmission between 2 to 5 seconds. If the gear lever position is changed during this phase, the new gear lever position is delayed.
This function is very sensitive and may respond too quickly.
Production Solution
- - -
Service
Check the TCM software per the software table below.
^ If necessary, update the transmission control module per the software table below
^ If the software is already at the newer version or higher, open a Technical Assistance Center (TAC) ticket and call a TAC consultant for assistance.
SVM Update Instructions
1. Follow all instructions in the attached TSB 2011732 00 Software Version Management (SVM), operating instructions.
2. Update the transmission control unit (217) using the SVM action code as listed in the table if necessary.
3. If the VIN is below 8K_9N004290 or 8K_9A126476, the forward and reverse clutches must be adapted after a software update. A clutch adaptation is not necessary on vehicles at or above this VIN break for this concern.
a. In Guided Functions, select Transmission Electronics >> Adjustment. After starting this function, the following question appears: "Have you replaced the control unit for the automatic gearbox?"
b. Attempt the GFF clutch adaptation test plan. If the test plans fails to adapt the clutches, perform the 0AW Self-Diagnosis Clutch Adaptation Instructions below.
Tip: If the adaptation is not possible in Guided Fault Finding due to a missing engine speed error, instructions for adapting the 0AW clutches with self-diagnosis are below.
0AW Self-Diagnosis Clutch Adaptation Instructions
Select the following measured values in the self-diagnosis and possibly save them under Favorites:
^ Adaptation of the forwards start-up behavior [LO] State
^ Adaptation of the backwards start-up behavior [LO] State
^ Transmission fluid temperature
^ Specified clutch torque
Creep adaptation of the forward and reverse clutch with 0AW gearboxes:
1. Make sure that there are no fault entries in the TCM.
2. Warm up the gearbox to about 85°C, ideally by pulling away in driving mode D and R at various loads of max. 1500 rpm.
Tip: Currently the adaptation is only possible when the measured value transmission temperature is between 80° - 95°C.
3. When the vehicle is standing still, select driving mode D.
4. Pull away with little acceleration to about 6 mph or 10 km/h. Slowly brake the vehicle with the foot brake. Hold the brake pedal for another 5-10 seconds as the vehicle stands still.
5. When stopping, the specified clutch torque must not drop below 20 Nm, otherwise the adaptation fails. If this is the case, change the driving profile (less load, gentler braking).
6. Repeat step 4 until the measured value indicates the adaptation of the forwards start-up behavior is successfully completed.
7. With the vehicle standing still, select driving mode R.
8. Repeat step 4 until the measured value indicates adaptation of the backwards start-up behavior is successfully completed.
When stopping, the specified clutch torque must not drop below 20 Nm, otherwise the adaptation fails.
If this is the case, change the driving profile.
9. After a terminal 15 reset, the adaptation starts over again with status running. Keep the ignition switched on for at least six minutes after a successful adaptation.
Tip: The ignition must not be switched off during this time period.
Warranty
Additional Information
The following Technical Service Bulletin will be necessary to complete this procedure:
^ TSB 2011732, 00 Software Version Management (SVM), operating Instructions.
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service manuals for the latest information.
Attachments - 00 Software Version Management (SVM), operating instructions