1990 accord ex. Power locks don't work. There is a clicking sound inside the drivers side door when the putton is pressed. Also, I don't know if it's related but the front R and L speakers are wired into an after market CD player but don't work. I diid pull and clean most of the wiring harness connectors under the dash.

 

Inside the door panel is a control box, held in by 2 phillips screws. You can remove it and then slide the circuit board out the bottom. Then you can find the cracked solder joints on the circuit board, resolder them test it and reassemble.

 

Make sure to check the fuse for power lock and unlock in the driver side kick panel. The fuse is probably working since you can hear the clicking sound. You can buy that control box from a junk yard, it should be cheap. Visually inspect the box to make sure you see sign of wear. There is also a chance that your actuator is not working. Thats also located beind the door panel.
Make sure to check for any loose wires. Make sure that the metal rod from the actuator isn't bend or broken going to the lock it self.