I know there is other posts on this subject and I have read them. I am having a problem with the locking system on a 260e 1987. No voltage at pump...tried taking pump out and apply voltage from another source....pump does not run. Is it suppose to with volts applied? The vacuum lines are tight, I can actually lock and unlock with manual slight pressure or vacuum. Fuse is good. I can find the no volts problem with some effort. Why would the pump not run with external 12VDC applied? Two problems here? Locks were giving me a problem when it got real cold but worked after car heated up. Now....nothing. Any input on this would be greatly appreciated. Thanks!