I just installed a remote entry unit in a 1992 300E.

The unit works fine, locks and unlocks all doors and trunk, both with the key or the remote.

When I tested the factory alarm, it works fine when locked by the key, it arms and disarms.

When locked with the remote however, the alarm doesn't arm therefore doesn't work.

The remote module is wired in series at the blue (drivers door lock) wire at the vacuum pump as per instructions and this part of it works properly.

Any help/suggestions appreciated,

Acky