How to clean 12 volt connections

Caig D5 Deoxit- spray, then plug and unplug a few times.

Contact Cleaner from NAPA.

Works great when label directions are followed.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Electrical-Parts-Cleaner-MAC-Electronic-Cleaner-11-oz/_/R-MCR4710_0057062154

They make a 7 hole wirer brush that cleans these out. Try NAPA or Auto Zone for this tool.I had one when I was a truck mechanic

Even Caig DeOxit D100 needs help on a badly corroded surface. But the combunation of the cleaner plus that afirementioned seven brush cap cleaner would work well. Flush out the residuewith brake cleaner.

My opinion of the rest of the contact cleaners is it leaves corrosion and oxidation intact but perfectly clean.
Not a speck of dirt or dust on the corrosion.

I just used D100 on my Weller 260 watt soldering gun. Where the copper tip gets allen screw fastened to the aluminum socket tubes. Apparently D100 works miracles just as well on aluminum as it does on copper or tinned surfaces (gold too).

After 11-years in service this thing acts like a different gun. WOW! It heats the tip in a fraction of the time it took even brand new. Aluminum + copper is bad juju.

Some thing to chew on: if that trailer plug is so bad in the socket contacts it's going to be every bit as compromised on the other end. Replacement and renewing of the copper wire strand shininess is by far the best choice. I use silicone dielectric grease and it works well - for years and years.

OK here's a old school way to get them nice and shinny. Get a can of COKE pour it in a container that the connector will fit in. put the connector (or battery terminal) in the bowel of coke for a couple of minutes. pull the connector out and see if the corrosion is all gone. Wash the connector out with water, dry it out (air hose works real good) then treat the connector with silicon grease, and your ready to go. You can use de-ox-it instead of water.

When that badly corroded I just replace with new.

Strip wire back, new screws to connect to and new blades on plug.

Heck of a lot easier/faster than trying to clean up corroded contacts.

Thanks for the suggestions. I'll try the commercial products but remember the Coke trick in case of emergency. If I replaced everything that gave me trouble,I wouldn't have money left for fuel.
This plug isn't the first and likly not the last of this type problem. I figure a one time investment of $15 will fix several other issues as they come up.

I like Coke, it leaves the connection just as corroded but nice and sticky. Sorry. I tried this a dozen times and it does not even work that good on fuzzy green battery terminals. Boiling hot white vinegar followed by dilute baking soda does work. But nothing is as good as replacing the connector with a new one.