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In the boot on under the carpet on the right hand tail light
it can be the vacuum pump that is not working.the vacuum pump is in the boot on the right hand side. remove cover, put hand on vacuum pump and feel if it starts when remote is pressed
This is the central locking vacuum pump and is located within a protective foam shell and secured by a rubber strap.
The air tube that connects the pump to the door that isn't unlocking has a leak somewhere and needs to be replaced.
in the boot on the drivers side.
Vacuum pump the same vacuum pump that works automatic locking hubs on the 4wd
First of all, there's no such thing as a 1989 450sl...they stopped making 450sl's in 1980...then they went to the 380sl for a few years, then finally the 560sl to finish up the 107 body style run. Secondly, if we are talking about a 1979 450sl, there is no central locking pump. The entire central locking system uses the engine's vacuum. There is a storage ballast underneath the front right fender....it reminds me of 9 black balls stuck together with a single vacuum line coming out of it. The doors, trunk and gas flap are all controlled by the central locking system. Each has and needs its own vacuum diaphragms...that are powered by the vacuum lines. If your central locking system isn't working, get a vacuum gun and test each diaphragm to see if they're working properly. There is also a small vacuum valve in the left door that might also need replacing...you should also check all the pertinent vacuum lines and rubber connections for leaks. One leak will screw up the entire system. Also, if you do have a 79 SL, you also have the worse climate control system ever made...this system also depends on a vacuum supply to function. That is a highly complex system that your mechanic should work on, not an amateur
The central-locking system is pneumatically powered. The bi-pressure pump for the system is located in the rear of the car and can be heard during operation. Note: If the central locking system stops working but the pump can still be heard, this indicates a leak in the vacuum circuit. This is usually a result of a vacuum pipe becoming detached at a rubber coupling (check connections at the base of the 'B' pillar, under the carpet).
That pump operates the pneumatic central door locking system.
A new central locking pump is needed.
A pump that locks.
It is located under the backseat, next to the battery. This is for w210 model E class.