my 98 sl500 central locking system quit working. replaced pump with another, yes it's used but from a reputable source and tested. now remotely doors lock and trunk pops open but won't unlock doors or unlock fuel door or unlock between seat storage. doors and storage will unlock manually with key. turn signals light when remote pressed so there is communication between car and remote. any help appreciated. curious as to where vacuum chamber is located and which systems work on vacuum and which work on pressure.

 

All locking elements work on both pressure and vacuum. If your turn signal lights lamp once or three times depending upon whether you are locking or unlocking the vehicle, then it seems likely your pump is defective.

 

All locking elements work on both pressure and vacuum. If your turn signal lights lamp once or three times depending upon whether you are locking or unlocking the vehicle, then it seems likely your pump is defective.

I'd open the trunk lid, and I'd remove one of the pneumatic connections to the pneumatic pump located above the battery. Then alternately lock and unlock the car using the remote while placing a finger over one of the exposed ports. You should be able to discern whether the pump is able to produce both vacuum and pressure.

 

Is this something new for 98? My 97 does not do this.

 

A '98 flashes the lamps. I'm not sure about your '97.