A/T - Features and Diagnostic Information

Group 24
Automatic Transmission



Bulletin Number
24 03 89 (1866)



Woodcliff Lake, NJ
May 1989
Technical Dept.



SUBJECT:
New "E9" Version AEGS/EH Automatic Transmission Changes


MODELS:
1989 535iA, 735iA, 735iL, 750iL

Note:
As previously mentioned in S.I. 24 02 89 (1860), the new E9 AEGS System was phased into production during September - November 1988. Consequently, some early 1989 models were produced with the previous E7 version AEGS system.

Prior to any AEGS transmission system diagnosis or component replacement, the AEGS version (E7 or E9) must be visually determined per S.I. 24 02 89 (1860).

Situation:
The new E9 version AEGS/EH system, while similar to the previous version, has subtle differences which could affect diagnostic and troubleshooting procedures.

This information should be used as a supplement to the comprehensive information presently available in Group 24 of the Diagnostic Procedures Manual (dated 9/88).

Interchangeability:
Unless specifically indicated in the parts system microfiche, absolutely no E7 and E9 AEGS/EH system components are interchangeable.

Shift Solenoid Activity:
Forward drive gear changes are achieved in the same manner as with the previous E7 system. The most important point of the E9 shift solenoid operation is that the sequence of activation is changed.

Forward Gear Operation:





The chart shows normal shift solenoid operation for the foflowing conditions:

- Program switch selection = A (E)

- Driving range selector position = Drive

Note:
Shift solenoid activation checking must never be performed on public streets or highways. These checks can be made in the workshop provided the following measures are taken:

^ Vehicle raised on a hoist with the rear axle free to turn.

^ Vehicle rear suspension supported with jackstands to bring the rear axle operating angles to the normal "loaded" plane.

^ BMW universal adapter in series with AEGS/EH transmission control unit and T.C.U. harness (connections must only be made with the ignition switched OFF).

Reverse Gear Operation:





The chart shows normal shift solenoid operation for the following conditions:

- Driving range selector position = reverse with vehicle stopped.

- Driving range selector position = reverse with vehicle moving forward > 3 MPH.



High Speed Downshift Protection:
4/3 Downshifts are inhibited when the road speed is approx. > 105 MPH.

Failsafe Running:
The AEGS emergency program function control remains unchanged. When the system self-diagnostics monitor a problematic situation, valve body power is shut-down at TCU Pin # 1 and the check control system displays the fault "TRANS PROGRAM".

However, the failsafe running feature now selects the 4th gear range as indicated in the forward gear shift solenoid activation chart.


Warranty Status:
Information only.