BenzWorld Junior Member
Date registered: Apr 2009
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
560 SEC - central locking electrical problem
Greetings for Oxford, UK. I have never posted to this forum before - however have been helped by the information here numerous times.
My current issue is with my central locking (W126 560 SEC) which recently stopped working. Having scoured the forums for all information on the vacuum locking system, I have checked all I can think of:
- There are no vacuum leaks. Disconnecting the yellow pipe from the PSE pump and sucking / blowing will cuase the doors / fuel flap to lock / unlock.
- I have tried a replacement PSE pump (sourced on eBay)
- I have measured the voltage accross the terminals of the rectangular power connector, this shows a solid 12v
-The issue appears to lie with the voltage level at the control wires (leading into the round connector). With all doors unlocked I can measure only 0.1 - 0.3 volts (negative lead of meter on the ground of the power input, posotive lead on each of the control wires in turn). When I lock the doors, the voltage drops to 0. I have tested each lock and the results are the same.
The other day, after a long drive, the system started working correctly from all doors / boot, however after a few hours was inoperative again.
So - I think I have ruled out
- Vacuum leak
- PSE pump fault
- Power to PSE pump
- Door lock actuator fault (as when system briefly started working, it was correctly from all doors)
It would seem that all is left is the very low voltage at the control wires (and I have no ideas why this should be). Any help would be very much appreciated as I have run out of ideas!