Warning buzzer switch - Central door locks??
 

I have tried to fix a central lock problem on my '91 300CE for a month now - 2 brand new Hella pumps, used ebay one, troubleshooting etc. I have a new pump installed, but I'm not getting it to run when I turn the key, even though I have 12v to the pump. I am assuming that when I turn the key - either to lock or unlock - current isn't flowing to ground and then to 12v. None of the doors or the trunk are activating the pump...so I'm assuming a bad electrical connection somewhere.

According to the FSM wiring diagrams, the warning buzzer switch on the steering column is a possibility. Does this sound possible - and how can I check the switch?

ryan

Bump - can anyone offer some guidance here?

I have done some further testing so let me add a few details:

1) The new pump works. Put it in my 560SL and it ran perfect.
2) I have voltage and no voltage as I turn the key in the driver's door and the passenger door at the pump connectors, but NOT the trunk. No voltage change when locking/unlocking the trunk.
3) And, I have no voltage at the connector to the trunk actuator.

Does it make sense that if the trunk has an electrical problem, the whole system is 'shorted' out?

So, where do I go from here? FSM says - with no voltage at actuator connector - to check 1) contact of connector, 2) continuity of cable terminal 30 (rt/sw or br/ws), 3) ground cable (br/sw or br/ws), 4) warning buzzer contact S8/2 and its ground cable (brown), according to wiring diagram.

Trouble is, I'm not sure how to do this?

ryan