Do you have AC in your cab that is no longer working?

 

No.. there is no ac as mentioned in earlier post. The cab doesnt even have a ac button. Thats why i didnt think it was a AC wire due to there never was AC

 

As was mentioned earlier, Toyota wiring harnesses usually carry all the wiring for options, even though yours might not have it.

A better help would be the colour coding of the wire.

What year is your vehicle?

 

Solid black.

 

Does your truck have a tach?

 

unfortunately no

 

well checking the manual the only thing it can be is the a/c as stated befor or your starter relay, and if its running i doubt its a starter relay wire. check the downloadable manual that a sticky, those are the only 2 full black wires in that area

 

if its a 10 gauge and all black it might be a engine ground!!!! check to see if theres any wire clips that look like the wire got riped out of there should be one on the intake man. and on the block you might have had one there it just got pulled off thats all

 

i'm with just a 22re - 10 gauge is way too big to be for the a/c clutch, or really for any sensor. most of that stuff is 18-14 gauge. my money is on ground, but if everythings running ok i would tape the end up and tuck it nicely out of the way.