This is the ONLY coolant sensor the ECM sees. It tells the ECM, obviosly, how hot the motor is so it can go into closed loop and aids in determining proper timing & fuel mix.
ECM coolant sensor
84-88 all 10045847 blk & yel L4- thermostat housing
85-88 all 25036979 V6- RH top of engine
near thermostat
From: Tin Man
The coolant sensor (to the ECM) varies the resistance.
The Pontiac Service Manual lists:
(approximate)
F C OHMS
210 100 185
160 70 450
100 38 1800
70 20 3400
40 4 7500
20 -7 13500
0 -18 25000
-40 -40 100700
From: Scott Backer