Control Module - (HFM-SFI) Modification

TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: April 1994

REF.NO. MBNA 07.5/1

SUBJECT:
Engines 104, 111 HFM-SFI
Modified Control Module

Starting January 1994. a modified engine control module containing vehicle equipment version coding was phased into production. As of March 1994 production, all HFM-SFI engines are equipped with this modified engine control module.

Coding

Coding can only be performed using the Hand-Held Tester (HHT) either automatically or manually. The control module also contains code protection.

During the coding procedure, the HHT's serial number is automatically entered and stored providing a reference to the dealer where the coding was performed.

When replacing this version of the engine control module, the existing code number must first be read with the HHT (menu selection 6, "Version coding"). After installation of the replacement control module. the previously read code number must be entered.

Note:
Until the successor of the HHT module 7/93 (124/129) and 9/93 (140) becomes available, the programming of the engine 104 HFM-SFI engine control module in models 124, 129 and 140 can be done with the HHT module 12/93 (model 202).

Should the code of the existing engine control module be unobtainable, it will be necessary to determine the vehicle equipment version and to manually enter the respective 9 digit code (obtained from the Spare Parts Microfiche, Group 54) via the HHT.

For the coding process, the following vehicle equipment versions must be determined:

^ Vehicle model,

^ Catalytic converter/non-catalytic converter,

^ Manual/automatic transmission,

^ 4-Speed/5-Speed automatic transmission,

^ Cruise control,

^ Acceleration slip regulation (ASR),

^ Electronic traction support (ETS),

^ Country version (USA).

Note:
Coding must be erased if the replacement engine control module is not needed after all.

The automatic recognition of vehicle equipment and or version feature has been eliminated. The maximum engine RPM for non-coded engine control modules is limited to 3200 rpm (limp-home mode).

Repair note:

When using an engine control module having the same part number, but coded differently, as a trial installation from another vehicle. note the following:

^ Read and note the code number of the engine control module of the vehicle being diagnosed.

^ Swap the engine control modules.

^ Read and note the code number of the trial engine control module from the "known-good" vehicle.

^ Enter the code from the vehicle being diagnosed into the trial installation engine control module.

^ Perform a function test of the engine control module.

^ Re-enter the original code noted for the trial engine control module.

^ Swap the engine control modules again, returning the engine control modules to their original locations.