I just bought a 1994 E320 coupe.
When I got it the interior light wouldn't shut off with the door, central locking didn't work at all and the seat belt presenters didn't work but as it was both sides I figured it was a relay and I'd fix it later.
Today on the way home I heard a rhythmic clicking like the hazards flashing but they were not. When I turned the lights off at the switch they were flashing.
I got out and turned the key in the lock to turn them off and it did and of course suddenly the seat belt presenters and the inside light work.
Now the great part…It won't start. I've tried locking and unlocking from both doors and the trunk. When I lock the car with the key the lights immediately began to blink (the alarm horn was unplugged when I got the car).
In addition to complicate matters I found a CodeAlarm box installed under the rear seat. U unplugging and re-plugged the box did not help or hurt.

Mercedes Alarm relay? Multiple relays? Short? This parasitic alarm box? I don't know.
I've ordered some literature on the 124 to help but it of course has not come yet.

Any ideas?
Thanx, BKH

(posted in general tech too)

 

Hi,
Don't know much about your specific model of Merc but suggest that the PSE unit which controls the Interior Light, Door Locking, Security etc. is faulty.
My own experience on an SLK suggests that these units are EXTREMELY sensitive to the slightest damp which tracks down the wires into the unit and adversely impacts the CAN (communication system between various other "computers" around the vehicle).
Suggest you remove the connector blocks from the PSE unit and observe whether there is ANY corrosion on the pins or block (Bluish deposit). Look VERY carefully. If there is then it looks like you will need a new unit. circa £250 I believe.

If you get your Merc dealer to connect their STAR diagnostics to the vehicle systems (chargeable although this only takes 15mins or so) and get a print out of what the On Board Diagnostics tell you. get a copy of the printout. This should show if there is a CAN, or other fault, and also identify which ECU / Module is the cause. This check needs to be done with a scanner that can communicate with ALL ECU's rather than just the Engine/Trans ECU.

Are you USA or UK based?

Stuart

 

Hi guys,
I'm U.S. based ... and I got it fixed at the local independant MB / BMW (ewww) fix it shop.
Was a faulty relay.

BKH