i am hooking up a 02 simulator today. my o2 sensors have 4 wires i need to find the signal wire a hot wire and a ground. what collors are these wires? what do i do with the 4th wire is it just not used?

 

i have 2 brown wires and one tan and one purple

 

you shouldnt have to splice O2 Sims, are you talkin about o2 extensions???

 

no not extensions. it is a simulator for the rear o2s it is a box with a power ground and signal line it goes in place of the factory o2 sensors (replaces them) the sensors are completly unpluged i just need to know which of the for wires that the factory o2 sensor pluged in to is the signal wire.