Coolant Temperature Switch (Oxygen Feedback Only)

Located on thermostat housing (all 4 cyl. engines), on front of cylinder head (all 6 cyl. engines) and on right front of intake manifold (all V8 engines). Sensor signals computer and prevents changing of air/fuel ratio until engine reaches 150° F. When engine reaches 150° F, switch allows computer to change air pump injection point from upstream to downstream and allows charcoal canister to purge itself. V8 engines use 2 different temperature sensors. If equipped with computer part no. 4145003, switch operating temperature is 150° F. If equipped with computer part no. 4145088, switch operating temperature is 98° F.