I have searched on this, but haven't found a solution to this particular problem on my 96 SL500.

The central locking system works perfectly with the IR remote, but will not lock or unlock with the key from the driver's door or the trunk. I have tested the wiring and microswitches in the door and trunk at the vacuum pump connector, and they are OK. The pump receives a ground signal when I lock either, which goes to unground when I unlock. I believe that this should cause the pump's controller to lock/unlock the car.

Pulling the fuse had no effect.

So is this another case of pump controller failure? Or are there other tests or tricks?

Thanks,

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe