Hi,
I have a w124 T 250 D from 1988. At the moment i have some problems with the central locking system.
The central locking system is connected together with comfort electronics (closing all the windows) and a non MB alarm system. This setup worked fine for several years now. i used the alarm system remote controller to close/open the doors. There is a central switch too on the middle consol to operate the central locking from inside. The two front doors are keyless only the tailgate has key.
Recently the automatic window closing stopped working then a bit later after closing the car the opening worked only after several try (pushing the remote contorller several times). Changed the battery in the remote controller, symptoms did not change. Now the central locking does not work at all, nor the inside swith on the middle consoll.
If i push the "buttons" on the front doors, system works, pump closes the other doors. If i open the closed doors from inside all other doors open too. However the tailgate key closes only the tailgate but the pump does not operate. Pushing the button on the tailgate also does not close the other doors. Checked Fuse C: ok.
I would like to ask anyones opinion what else to check before i would buy new relays or other parts.
thanks
Andy

Your model was not imported into the USA and the "convenience" or "comfort" relay was not available in the US for a year or more after your car was made. The console-mounted central locking switch also may not have been installed on W124s bound for the US although it was offered on other models and years. This and the after-market alarm makes it harder for us Yankees to help you diagnose the problem.

Since the system worked at one time, I would look at things that have changed or could have changed with time. Did you or anyone else do any work on the car (install a stereo, for example) that could have messed with the wiring? Also, these cars were known to have problems with the wiring that goes from the B-pillar into the rear doors; my '87 300D sedan had such problems. The stranded wire chosen by Mercedes had strands that were too coarse; after years of bending back and forth, they would break and/or cause short-circuits. I had both problems in my '87. This could cause the symptoms you report. The front door or tailgate wiring could also be the source of these problems. As you know, the central locking, convenience relay, and alarm are all interconnected. I would re-check the fuses first; don't just look at them, remove them and make sure they aren't cracked. There may be several fuses involved so check all of them. Also, check all of the wiring or as much as you can get at before checking anything else.

Jeremy

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Thanks for the input. I have looked carefully and found some moisture around the cable to the IR Panel. Probably in the main time it dryed out, because the next day the system worked again.
Andy