1)I'm experiencing my headlights flashing on and off when I open the car door.2)My door locks do not open when I unlock the driver's side door or the passenger side door.What could be causing this to happen?
1991 190e 2.6.

The only time this happens to me is when the alarm sensors are triggered off (and the engine wouldn't crank too).

Otherwise, I think it could be an electrical wiring crossed which might take more time to analyse and detect the sequence.

When did you notice this, and can you report any other incidences prior to this happening, i.e. dashboard lights/indicator lights flashing, intermittent loss of power?

Your doorlocks could be due to the central-locking pump. Just a hunch.

Well,
your alarm is armed and disarmed everytime you lock/unlock your doors. You may want to investigate/clean/lube your locks and check your central locking pump like ymsin said.

My alarm used to be armed 1 minute after the doors are shut and no movements are detected. Thus, sometimes when I forget and breach the alarm, all lights go loose. After awhile, I had that disconnected by a master reset.

In any event, I would think that some wiring detection might just be whats required. It would be much easier if we had the car posted right here and where we're able to work on it with more precision and method-o-logically.
:)

This happens to me just recently. I have this 88 420 SEL, and the alarm goes off while driving. I mean, ..the horn was activated and the lights were flashing. I was pulled over by the CHP, ..they think that I have some kind of emergency or that I stole the car...?? As per MB DOC, there could be something wrong with the micro-switch at the door handle or the ECU for this alarm is defective.
I did tried using my MASTER KEY, ...I stick it at the keyhole for 30 minutes, ...I let the computer read it. So far, ...so good. No more horn and lights that flashes.


I hope this could be of help to you.

Any developments, DadMac?

I beleive you have a problem in the central locking system. You will soon experience the doors locking by themselves and it may even lock you out. My trunk lock/actuator assembley is going bad. The car sometimes locks when I hit a bump, slam the door, etc. When this happens. I get a close encounter of the third kind. The headlights and taillights begin to flash and they wont stop until you lock and unlock the drivers door with the key.
Well I got the lights to stop flashing by disconnecting the wires to the alarm system, under the passenger floor panel. I decided to disconnect the alarm after reading a post with the same problem. I was easy. I set off the alarm by setting the alarm and opening the door standing outside the car and opening the driver door using the inside door release (window rolled down). The alarm would go off and you can hear the system tick like a bomb. Then trace the wires under the passenger floor panel and find the wires that it takes to shut it down.