if you still have problems after resoldering the pins and when you move the connector it flashes on and off then replace the connector (the one with the wires) and replace the pins or give them a light sand with very fine sand paper.

it could be dry / cracked solder joints or it could be the pins inside the socket that the wires are connected to (some times they loose their grip on the pins that are soldered to the board so they become hot due to the resistance and expand more), or it could be a problem with the connection between wires and the socket. The wires are pushed onto the pins inside the plug when they are made which cuts through the insulation on the wire and contacts the conductor inside the wire.

if you replace the plug on the wires use the molex plugs with the pins that are crimped to the wires not the ones that are pushed on like the one that is on there (use the one on the left in the picture. the one on the right is the original type of connector used from factory)