A/T - Modifications of the AGS Transmission Program
Group 24Automatic Transmission
Bulletin Number
24 01 95
Woodcliff Lake, NJ
May 1996
Product Engineering
This Service Information Bulletin supersedes S.I. 24 01 95 (4259) dated August 1995; please remove it from your S.I. binder and discard.
Asterisks identifies changes made to this revision.
SUBJECT:
AGS transmission program functions
MODELS:
540iA vehicles (with M60) produced 9/93 - 5/95
740iA/iLA (E38) vehicles (with M60) produced 9/94 - 5/95
750iLA (E38) vehicles with (M73) produced 1/95 - 6/95
Complaint:
1. Customer indicates one of more of the following:
^ Does not like the current shift program.
^ Transmission holds gear too long/hangs in gear.
^ Shift points are unpredictable.
^ Down-shifts while going downhill and braking (hill program).
^ Unexpected shift when going uphill (hill program).
*2. Trans Program displayed on the instrument cluster matrix display and any of the following fault codes may be stored in the transmission control module: *
^ 1, 4, 5, 29, and 51 ^ 100 ^ 101
Correction:
To address the above listed complaints, several changes have been made to the original AGS transmission shift programs as a result of concerns expressed by our customers and the media.
The latest program changes were introduced into production vehicles and can be identified as indicated:
The following information will provide a brief explanation of the various functions associated with the AGS system and the changes made:
Fast-off feature:
During rapid deceleration, the transmission holds the gear that it currently is in until the driver reaccelerates.
Software Change:
Elimination of Fast-off function to avoid the sensation of "hanging up in gear."
Drive away evaluation:
The AGS system selects the appropriate shift program based on the amount of acceleration that occurs during take off.
(i.e., A full throttle acceleration will select the "Sport" program. If kickdown is reached, the "Extreme Sport" program is selected).
As an example: If a fast acceleration from a toll booth occurs, the transmission will remain in a sports mode oriented program for an extended period of time, even if the driver has already backed off the throttle.
Software Change:
Drive-away evaluation function has been dampened so that a full throttle acceleration selects the "Economy" program and kickdown will select the "Sport" program.
Kick fast feature:
The AGS system is equipped with four major drive programs:
Extreme Economy
Economy
Sport
Extreme Sport
Based on how fast the accelerator pedal is depressed, one of these programs will be selected.
Example: when accelerating to switch lanes or to pass, a more sport oriented program will be selected based on the vehicle speed and the amount of acceleration. In most instances a two gear downshift will occur. Due to a more sport oriented drive program, the transmission will also remain in a lower gear for an extended period of time, even though the driver has already backed off the throttle.
Software Change:
Eliminated "Extreme Sport" program which addresses the sensation that the transmission "hangs up in gear."
5-4, 4-3 and 3-2 downshift points on full throttle acceleration have been changed to allow for a single gear downshift at higher speeds, making the car feel more responsive. A two gear downshift is still possible if the accelerator pedal is quickly depressed to kickdown.
Driver Evaluation:
The AGS system evaluates the driver's use of the brake, vehicle speed, amount of throttle applied and the use of kickdown. Based on this evaluation the AGS system selects a drive program. If the driving style is varied (i.e., playing with the accelerator pedal, randomly accelerating hard for a short time period) the AGS system may misinterpret the driver's intention and select a more sport oriented drive program with higher shift points. By raising the shift points, the transmission will remain in a lower gear for an extended time period.
Software Change:
Kickdown and brake evaluation have been eliminated and a faster reset to the "Extreme Economy" program will occur.
Downhill Recognition:
When driving downhill with vehicle road speed increasing, the AGS system will down shift into the next lower gear once the brake is applied to support engine braking.
Software Change:
Elimination of downshifting to next lower gear. Transmission will hold the current gear to prevent an upshift.
Uphill Recognition:
When driving uphill the transition into the "Hill program" mode is usually associated with a downshift into the next lower gear. The hill program will also hold the current gear longer to prevent a pendulum shift when going uphill.
Software Change:
A downshift will not occur based on going into the "hill" program but rather on the shift points of the currently selected drive program.
Procedure:
In case of customer complaint:
1. Verify that the latest version software is installed, as per the table.
*2. Install the latest AGS transmission EPROM if the tester software number or the data status does not reflect what is shown in the table above. Please refer to S.I. 24 05 95 (4294) for instructions on removing and installing the EPROM.*
3. Once the new EPROM is installed, clear the adaptation values in the control module using the MoDiC or DIS.
To clear adaptation values, select:
a. "3 Service Functions"
b. "4 Pressure - adaptation values"
c. depress -> button to activate the clear function.
Parts Information:
Description Part Number
EPROM 540iA
with AGS 01 00 1 469 154
EPROM 750iLA (E38)
with AGS 01 00 1 469 155
EPROM 740i/iLA (E38)
with AGS 01 00 1 469 156
Warranty Information:
Parts and labor will be reimbursable under the terms of The applicable BMW New Car Limited Warranty.
Defect Code: 24 00 26 63 00
Labor Operation Description Flat Rate Units
00 51 094 Check software number and 7