Transmission Control Module Fault Code 40 (24 04 93 (3931))

TRANSMISSION CONTROL MODULE FAULT CODE 40

TECHNICAL SERVICE BULLETIN

TRANSMISSION CONTROL MODULE FAULT CODE 40

Model(s): E34 (5 series), E36 (3 series) with A4S 310R A/T

Group: 24 - Automatic Transmission

Bulletin No.: 24 04 93 (3931)

Date: January, 1994

COMPLAINT

"Trans Program" is displayed in the matrix (E34) or the transmission fault indicator is illuminated (E36). Cycling of the ignition restores normal operation. Fault code 40, pressure regulator, is stored in the fault memory of the transmission control module.

CAUSE

Investigations are still pending into the cause of this fault. Experience has shown that replacement of the pressure regulator does not eliminate this fault.

In order that we may bring this investigation closer to an explanation, we are requesting that all parts returned to the Warranty Parts Reclaim Center for this fault include a copy of the transmission control module identification page and output testcode along with the data in the RAM cells. When describing the problem and cause under 'Claim Comments by Defect Code,' please use the phrase "EGS Fault Code 40" followed by any other comments which you feel describe the situation. Samples of the Service Tester and MoDiC printouts are shown for your reference. See Fig 1 and Fig 2 .

CORRECTION

If the following troubleshooting procedure does not show a fault with the pressure regulator, the transmission control module is to be replaced.

REPAIR PROCEDURE

1. Read out the fault memory and obtain printouts of the transmission control module identification page, output testcode, and any data in the RAM cells.
2. Disconnect transmission control module and install 88-pin test adapter (special tool number 88 88 6 614 410) on to the harness connector.
3. With the ignition switched off, check that the resistance between pins 40 and 41 is within specification (2-6 ohms). Also check that there is not a short between this circuit and power and/or ground by verifying that there is no continuity between pins 40 and 19 and pins 40 and 37.
4. Repair faults found as necessary. If no faults are found, replace the transmission control module.