Rear Veiw Mirror Comp/Temp Question (yes one more)

Ok ..I have a 2002 Silverado 1500HD Crew 4x4 LS.. I added a comp/temp mirror to it. I pulled the wires down from the over head and it has the wires for the power and temp sensor in the plug. I went out bought the temp sensor because when the mirror is powered up it reads the direction and "OC" (open circuit). Ok my question is where would you find the PLUG for the sensor in the engine compartment?. If it's not there, were would you tap in to hook it up? I have the wires from the factory at the mirror, but can't seem to find the plug for the sensor in the engine compartment. Can anyone post a pic of there temp sensor loaction for me? I've gotten eveything under the sun but no real picture of the location. BTW I've done a few searches under this topic and no real good info.. Thanks