The alarm system arms when I lock the passenger door but the other doors do not lock. Where do you suggest I begin? I have a schematic but it appears that the wiring from the passenger door switch is intact since the system arms.

The central locking system operates properly when I lock the drivers door or the trunk(all vacuum actuated locks reposition and the alarm arms)

Start in the passenger door. The vacuum actuator is not working. The alarm arms because it is not actuated by the vacuum circuit. Uses a microswitch on the lock mechanism. You might also check the vacuum line where it passes from the body to the door. Constant flexing there..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

Vacumm Acuator
 

Do you need to remove the door panel to get to the vacumm actuator? I think my driver's side door vacumm actuator must be faulty. The driver's side lock, when turned, doesn't activate the central locking system. The trunk and passenger-side locks do just fine. Is replacing the vacumm actuator easy?

Years ago I tore the insides of my 87 300E apart. Had the seats, door panels, and whatever else I could remove out of the car and distributed across my lawn.

I finnaly found the culpret. It was a corroded wiring connector for the locking system located under the carpet and rubber subfloor where the right rear passenger would place their feet... about a foot and a half forward of the vacume pump.

So make sure you have current going to the parts before replacing them.