Keyless Entry: Service and Repair

Replacing components of the infrared remote central locking (models with drive authorization system stage 2)

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The infrared control module and the engine control module are permanently assigned to each other by an identification code. For this reason, the infrared lock system number portion of the lock system remains in the car over its entire life, in other words only the mechanical lock system number portion as well as the check digits may change.






Structure of a lock system number

What this means if a transmitter key or a mechanical key is lost:
- IRCL lock system number portion is retained -> invalidate lost key by desynchronizing the control module or by revocably or irrevocably blocking the relevant transmitter key.
- Change mechanical lock system number portion -> install mechanical lock system with new lock system number at all points. It is then essential to return a sticker with the 8-digit lock system number stating the FIN to Dept. VP/MAM2, Mercedes-Benz AG, 70322 Stuttgart.

What this means if the IRCL control module is faulty:
- IRCL lock system number portion is retained -> install new control module with the same lock system number.

What this means if a mechanical lock element is faulty:
- Lock system number is retained -> replace lock element while retaining the lock system number.

Revocably or Irrevocably blocking infrared transmitter keys (models with drive authorization system stage 2)
With the introduction of the IRCL control modules with the Part No. 210 820 27 26 / 28 26 as of about 09/95, infrared transmitter keys can be revocably blocked using the hand-held tester. This process of blocking certain transmitter keys is performed menu-prompted with the hand-held tester. Revocable blocking or revalidation of particular transmitter keys is possible as from hand-held tester module 06/95.

With the introduction of the drive authorization system stage 2 infrared transmitter keys can be irrevocably blocked with the hand-held tester. The procedure for blocking particular transmitter keys is performed menu-prompted with the hand-held tester. The irrevocable blocking of a particular transmitter key should only be performed at the expressed wish of the customer because a transmitter key has been lost.

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It is not possible to revalidate transmitter keys which have been irrevocably blocked.







All cars are factory-supplied with the transmitter key "1" and "2". The infrared spare key which is also supplied from about 05/95 will have the number "3". In addition, all consecutively numbered transmitter keys which may have been purchased subsequently should also be allowed for.
The existing transmitter keys are recognizable from the numbers stamped in the transmitter key housing. Remove the battery compartment cover on the transmitter keys and read off the identification digits.
This makes it possible to determine the number of the lost key which should be blocked.