I have an early 86 coupe (steel heads). There is (what appears to be) a plug or a broken-off sensor between the #1 and #3 cylinders. I also found part of a sensor lodged down in the subframe. It's white witha two-prong male connector. Any ideas what this is?
Thanks

 

On my 86 that would be the electric fan switch works off coolant tempurature

 

It is usually the place for the temp sender for the gauge in your dash which is a one wire sensor, usually green wire.

 

On my 87 vette it is the auxilary fan switch. It run straight into the altenator harness with one wire. Mine also broke. I ordered the new connector from Ecklers for $4.99 and fixed with no problem. No sure on the 86's though. I've seen many discussion on switches in these areas and they all swapped or changed from year to year. It's usually the aux fan or temp gauge for the cluster.

 

This may help from another forum from when I was also trying to figure this out. Hopefully it helps.

http://forums.corvetteforum.com/show...t=auxilary+fan