98 Buick park avenue, electric door locks work intermittently, lock while engine running and won't unlock!

Do you know how to use a wiring diagram an a DMM - digital multi-meter to test automotive electrical circuit's ? That's how one would go about solving a problem like this . Testing B+ power ,plus ground circuit's . Without testing the circuit's we'd only be guessing .Lock's are controlled by a electronic module. Could also have DTC'S - diagnostic trouble codes stored. Free wiring diagrams here http://www.bbbind.com/free_tsb.html
Enter vehicle info. year , make , model an engine size . Under system click on body & accessories ,then under subsystem click on power lock's . Click the search button then the blue link. Do the power windows work ?
The power door lock sub-system is comprised of the following components:
• The class 2 serial data link
• The door lock actuators (motors/manual levers)
• The power door lock switch
• The driver door module (DDM)
• The left front power door lock switch
• The passenger door module (PDM)
• The rear door module (RDM)
• The remote function actuator (RFA) module
• The right front power door lock switch
• The simple bus interface (SBI)

If you know nothing of the stuff i posted ,your best bet would be to take your vehicle to a qualified repair shop.

Driver Door Module (DDM)
The driver's door module (DDM) directly controls the driver's door lock actuator motor. The DDM receives and forwards the driver's door switch lock request messages to the remote function actuator (RFA) via the serial data link. The RFA receives the request message and examines the message for lockout prevention criteria. If the conditions are proper, the RFA sends a lock or an unlock command message back to the DDM. The DDM forwards door lock messages received from the RFA to the passenger door module (PDM) and the rear door module (RDM) over a simple bus interface (SBI) line. The DDM also contains a class 2 serial interface which communicates with other vehicle system modules. The left front door power window and the outside power mirror are also controlled through the DDM. Battery voltage is always applied to the DDM through the retained accessory power (RAP) circuit breaker located in the underhood Maxifuse® block.

Could be a simple problem , but one never know's till they do all the testing .

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