420a coolant temp sender to gauge

i have a 97 2g 420a motor. i hooked up all my other autometer gauges but cant find the signal to the stock temp gauge. i have a chiltons and i see 2 sensors, one for engine control the other a supposed sending unit....i tapped into the sending unit and my a/m temp gauge was pinned....so i tapped into the other sensor a gr/bl wire and a gr/wh wire...that just screwed the motor up during idle. ive heard that the signal to the stock gauge comes from somewhere else....does anyone know...any help is better than nothing...thanx

http://johnseclipse.tripod.com/welcome/id8.html

See if that helps

i checked out the link but it didnt say anything about water temp...thanks for the reply tho