I opened the diagnostic plug in for the first time today. I was just poking around to disconnect my stereo, I had never opened it before. I popped it open, and I got all this white/brown goo on my hand. The holes look pretty plugged with this stuff. It kind of has me worried...nothing has gone wrong and it has been there the entire time I've had the truck, as far as I know. The top "crust" is a bit brown, like it has been exposed to heat or something.... anyway, what is this stuff, and should I clean it off? It is covering basically the whole plug, even down into the little nodes themselves. Thanks for your help!

 

Its supposed to be there. Its dielectric grease of some sort. It prevents water getting into the contacts and causing problems. I use it on my sparkplug boots to keep water from getting between the plug wires and plugs.

 

Thanks! I'm glad I didn't mess with it, then!