Do a google search for "Bull Frog Electronic Cleaner". It is by far the best stuff I have found to take care of corrosion and keep it off.
http://www.amazon.com/Electronic-High-Performance-Technology-distortion-reliability/dp/B00WTH5ND6
Can you take the covers off the connectors to get to the back side (wire side), sounds like you may have salt or corrosion creating a high resistance short between two of the wires. Could be on either side of the connector and both sides need to be cleaned.
http://www.amazon.com/Electronic-High-Performance-Technology-distortion-reliability/dp/B00WTH5ND6
Can you take the covers off the connectors to get to the back side (wire side), sounds like you may have salt or corrosion creating a high resistance short between two of the wires. Could be on either side of the connector and both sides need to be cleaned.