Central Locking System Vacuum Pump Activation
 

How is central locking system vacuum monitored in the R129? Is there a sensor integral with the pump or is there a separate control unit? Could uncommanded operation of the pump in a system that has no vacuum leaks possibly be due to a fault in this pressure sensing circuit?

I once fixed a 129 for a similar complaint. The problem was a faulty glove box lock. Every now and then the pump was fooled into thinking that interior central locking was called for. 129's were the only cars with this feature. I hope this helps.