Hi all, I just got a beautiful 1994 E420 and I love the car. Weird thing happening is that the car locks all the doors if the trunk is closed to hard. Another weird thing happend to me yesterday while driving the car. I was going about 70mph and I hit an unavoidable bump in the road.(it waspretty good bump) When I hit it, all the doors locked and I continued driving. About 5 min. later, the alarm sounded and I pulled over and opened the door and placed the key in the drivers door and it the horn stopped. Today, I went outto the carand I opened the trunk. (it had been unlocked all day), and all the doors locked for some reason. I have a keyless entry remote that locks and unlocks all the doors just fine. What in the world causes this strange malfunction?

Is this a vacuum leak, or faulty PSE pump? Where should I start looking, under the rear seat?
Please, any help would be appreciated!!!!! The forums are great here, I have learned so much.

 

Hi Robinbird,

Interesting.

Since the locks work fine (lock/unlock) I do not believe that the problem is associated with the pneumatics side of the central locking system. The PSE covers central locking pneumatics as well as electronic control of the door switches and therefore also impact the dome light function. In addition the PSE covers Bulb failure warning + a few other circuits. HeatedRearWindow etc.

However since the alarm was activated at one point and a good bump/vibration caused the problem I would have a look at the jacking sensor. Can't be sure whether your spec. has one but it is a sensor that senses movement particularly tilt as part of the security system. Maybe it is loose or tightened up at an angle therefore more sensitive than it should be to tilt or bump in a particular direction. Usually located near the PSE / boot area.

Usual central locking problem is water ingress / condensation onto the PSE CAN (digital highway) connection. This can cause the weirdest of problems.

Is your internal dome light working correctly?

Stuart.

 

Hi, Thanks for replying. Yes the dome light works and the rear light as well, also the rear window defroster comes on too. Seems to have no other problems. I called an independent MB shop and the service person said he had never seen a problem like that before but would take a look at it tomorrow. Don't know if I should go to the dealer or not, trying to avoid the cost of the dealer right now!!