Initial Inspection and Diagnostic Overview
Diagnosis - Function Test [11]
General
This section is divided into:
- Checking condition of ATF (Initial evaluation)
- ATF level check
- Replacing ETC control module (N15/3)
- Limp-home mode functions
- Transmission adaption (adaption of the ETC)
Checking condition of ATF (Initial Evaluation)
1. Check ATF level, correct fluid level as necessary.
2. Review section 0 Scan Tool Testing and Procedures
NOTE: Prior to performing any repairs, readout the DTC memory from the transmission control module using the HHT (see Section 12). Reading and Clearing Diagnostic Trouble Codes
Visually inspect condition of transmission fluid.
- Contamination (excessively black transmission fluid color, pungent/burnt smell)
- Water in transmission fluid (milky white discoloration, streaked appearance)
- Metal shavings (metal particles, metal pieces)
The initial dosage of the red pigment in the ATF was too low. Since 10/97, the use of a higher dosage of red pigment in the ATF, has resulted in more stable red pigmentation. A purely brown or black coloring of the ATF does not have an effect on the friction value or function of the ATF, therefore, no fault is indicated regarding the ATF color.
ATF fluid which smells burnt points to a slipping Brake/clutch assembly. After finding the cause (loss of ATF, or seized servos etc.) and removing same, replace both the faulty items and the ATF.
Abrasion particles in the ATF:
Due to the relative movement between the transmission components after a short running distance, a fine "vail" of abrasion particles (gray for aluminum, yellow for brass) can be found in the transmission oil pan.
This "vail" abrasion does not effect the proper function of the transmission.
If there is however, found in the transmission oil pan, an extremely fine abrasion (graphite residue which when smeared on paper leaves a gray streak) or larger metal shavings (in the millimeter size range) then there is a mechanical fault within the transmission. Based on the complaint, the corresponding components of the transmission or the entire transmission must be replaced. When repairing the transmission, it is important to flush the oil cooler and the transmission hoses afterwards and the replace the ATF with fresh ATF. Replace the torque converter only if upon draining the ATF, metal shaving are found in the ATF
3. Inspect automatic transmission for external oil leaks (Determine source of fluid leak and repair).
ATF level check
When checking the ATF level, the temperature must be min. 60 °C.
The current ATF temperature as part of the ATF level check can only be read out using the HHT, with the transmission selector lever in "R, D, 4, 3, 2, 1".
Replacing ETC control module (N15/3)
Using the HHT, it is possible to send version coding data from the control module to a new transmission control module (with a later part number) being installed
(valid only for functional software: e 02 -> e 03
f 07 -> f 08).
Initial Evaluation Illustrations
Figure 1:
Extremely fine aluminum and/or brass abrasion particles
Transmission is serviceable
Figure 2:
Extremely fine graphite like abrasion particles
Mechanical damage to transmission
Figure 3:
Large metal shavings, in millimeter size
Mechanical damage to transmission
NOTE: Review S.I. MBNA 27/32, dated May 1998 concerning ATF fluid color as well
Electrical limp-home mode
In order to prevent damage to the automatic transmission in the event of an electrical fault, the gear currently engaged is held and the assigned diagnostic trouble code (DTC) is stored.
The limp-home mode comes into effect with the following procedure:
1. Stop vehicle.
2. Shift transmission selector lever to "P".
3. Shut off engine.
4. Wait at least 10 seconds.
5. Start engine.
After restarting engine, the vehicle can only be driven in 2nd or reverse gear.
NOTE: The engagement of "N -> D" and "N -> R" will be very harsh, since the electronic control of the automatic transmission has been turned off.
This type of limp-home mode can only reset by repairing the fault and erasing the DTCs with the Hand-Held Tester (HHT).
Mechanical-hydraulic limp-home mode
In order to prevent damage to the automatic transmission in the event of an mechanical-hydraulic fault,
- the transmission shifts into 3rd gear and is held in this gear, or
- the transmission shifts to the last "known good" gear and is held in that gear.
NOTE: This type of limp-home mode is reset by turning the Ignition OFF, and then ON again
Note: Hints regarding "D" shift points for passenger vehicles follows:
Up - downshifts using shift programs ("S", "W")
- Mode selector in "S": Transmission starts in first gear and shifts into first when coasting to a stop.
- Mode selector in "W": Transmission starts in second gear and shifts into second when coasting to a stop. First gear can be attained upon full throttle deployment.
(Caution! During engine warm-up the transmission starts in first gear and coasts to a stop in second gear).
- Shift points are increased: While driving up or down mountain passes, with heavily loaded vehicles, at very high transmission fluid temperatures, with transmission mode switch in "S", also: with abrupt throttle release, and very sporty driving style.
Downshifts using shift program at full throttle with mode selector in "S" (only from gears 5->4 and 4->3)
- Upon rapid throttle release; an upshift into the next higher gear is prevented and selected only when vehicle has decreased lateral acceleration rates and appropriate handling characteristics. This prevents skidding of the vehicle in curves.
- At full throttle deployment, the downshift occurs at higher speeds.
Downshifts using shift program at kick down with mode selector in "S"
- The kickdown downshift in transmission mode "S" is lower at ATF temperatures < 40 °C
Note: Hints regarding "D" shift points for Model 163 follow:
Up - downshifts using shift program ("D" shift points)
Tranmission starts in first gear and shifts into first when coasting to a stop.
Shift points are increased while driving up or down mountain
passes, with heavily loaded vehicles, at very high transmission fluid temperatures, with abrupt throttle release, and very sporty driving style.
Downshifts using shift program at full throttle with gear selector lever in "D" (only from gears 5->4 and 4->3)
- At full throttle deployment, the downshift occurs at higher speeds.
Downshifts using "kickdown" with gear selector lever in "D"
- The kickdown downshift in transmission is lower at ATF temperatures < 40 °C
Transmission Selector Lever "D" Shift Points
Model 129.063/067:
Model 129.068/076:
Model 140.032/033/043:
Model 140.051/057/070/076:
Model 163.154/172 (Up To 01.31.00):
Model 163.154/172 (As Of 02.01.00):
Model 170.447/449:
Model 170.465:
Model 202.023/024:
Model 202.028/029:
Model 208.365/370:
Model 210.020/025:
Model 210.055/065/265:
Model 210.070 With 722.623/632 & 210.072:
Model 210.082/083/282/283:
Transmission adaption (adaption of the ETC)
Definition
Transmission adaption optimizes shift comfort through the automatic matching of data.
In order to compensate for tolerances and wear, there is an automatic matching of:
- Shift time
- Fill time
- Fill pressure
- Activation of torque convertor lock-up clutch
The retrieved data is indicated by the HHT via menu selection 07. The data can also be reset using the HHT.
Thereafter, electronic control of the transmission must be re-adapted to the transmission using the adaption procedure.
Requirements
- ATF temperature must be a min of 60 °C to a max. of 105 °C.
- A/C system OFF.
- Connect HHT to data link connector (X11/4) according to connection diagram. (see Section 0) Scan Tool Testing and Procedures
General
There are two possibilities to perform the adaption:
- Perform a test drive, using a second technician to observe the data as indicated by the HHT via menu selection 03, or
- Use a vehicle dynamometer.
NOTE: Re: engine rpm limit:
It is important not to exceed the specified engine RPM during the adaption procedure, as in this case, adaption of the transmission will not take place.
Engine Torque Values:
See Engine Torque Value Tables Below.
Adaption procedure
Caution! During the adaption procedure, it is important to maintain the engine torque values as Indicated in the Engine Torque Value Table on the following page.
1. Following the replacement/swap or repair of a transmission, the following shifts must be newly adapted after resetting the values:
Acceleration upshifts
- 4 X the 1 -> 2 shift
- 4 X the 2 -> 3 shift
(Torque values: see Engine Torque Value Table Below).
Additional note regarding adaption procedure after replacing a transmission:
Print all adaption data as indicated by the HHT and return this data with the returned transmission.
2. In case of complaints regarding shift quality, the following shifts must be newly adapted:
Acceleration upshifts
- 4 X the 1 -> 2 shift
- 4 X the 2 -> 3 shift
- 3 X the 3 -> 4 shift
- 3 X the 4 -> 5 shift
(Torque values: see Engine Torque Value Table Below).
Deceleration downshifts (while coasting)
- 3 X the 5 -> 4 shift
- 3 X the 4 -> 3 shift
(Torque values are not needed for these shifts).
Upon completion of the adaption procedure, allow the engine to idle for an additional 10 minutes. This is necessary, so that all indicated values from the HHT are transmitted completely into the DTC memory of the transmission control module (N15/3).
If this does not occur, or if only some of the values are stored in the DTC memory, the transmission must be re-evaluated after a subsequent test drive.
