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Outstanding Contributor
R129 500 SL 1991
2,115 Posts
Assuming your car is MY 1995, I believe it would have DAS1a authorisation. I assume you point the IR at the doors, you don’t have a receiver on the rear view mirror, correct?

The receiver on the door sends the signal to the infrared remote central locking (IRCL) control unit, which decodes the signal, and if the code is correct, it actuates the anti theft alarm (ATA) and PSE controller unit, which pneumatically activates the central locking (CL).

The receivers, control units and actuators (PSE) are hard wired on a MY’95, so they do not operate like a more modern faster CAN BUS system.

You say your IR does not work on any door, but you can start the engine? Please confirm. Unlocking the door locks with the key DOES NOT activate/deactivate the ATA. So I assume your ATA is currently deactivated.

From the start of 1994 all R129s had an immobiliser as standard. Because these older systems can be finicky, some BW members just don’t use the convenience feature anymore, they just use the key to avoid activating the ATA and not being able to start their engine. If you are not sure what you’re doing, don’t do anything that might inadvertently activate the ATA, just in case you cannot deactivate it.

The IRCL can be resynced by pressing the IR at a door/trunk receiver, then switching ignition on within 30 secs. AFAIK a replacement IRCL does not need to be reprogrammed other than resyncing.
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