Hi Al here, Im new to the forum so pardon me if I make errors. I have a 2002 Ford Ranger with 4.0 The upstream 02 sensors are 4 wire sensors, each has 2 White wires, 1 Black and 1 Gray. I am trying to identify which wire is the Signal wire, I suspect that the 2 White wires are for heat, but Im not sure. Any help on identifying the Signal wire would be greatly appreciated, Thanks

 

Hi Al.. Welcome to the site..

Check the wires colors/tracers on the trucks harness/connector side.. Might help if checking unplugged..

The signal returns are Orange..

Input for #11 is Grey/Light Blue, and #21 is Red/Black..
Voltage in Start/Run isLight Blue/Orange
Heater #11 is Red/White, and #21 Yellow/Light Blue

 

Hayapower, thanks for your input.
I have to say right off the bat, Im no electrician and to be honest your info is a bit over my head. I did check the schematics after your post and the only diagram I have shows that the returns are indeed orange, but I can't seem to locate the others you listed. Perhaps if I explain what I am attempting to do, you could shed some of your knowledge in laymans terms. I run a Hydrogen Generator on my truck, to maximize it I need to wire in an EFIE board to control voltage signal from the 02 sensor to the ECU, otherwise due to the HHO the sensor reads it as a much higher 02 content and richens up the mixture thus my mileage pretty much stays the same. Wiring of the EFIE is quite simple if the signal wire off the 02 sensor is known, but my experience is very limited in regard to the 02 sensor wiring. I would much rather be able to do the splice up on the firewall, but I know the wire color changes between the 02 sensor and the connector which is why I was asking about the wires which come directly off of the sensors. being able to splice without having to work in tight places from under the truck would be much easier, but it would be better than making a mistake up topside. Thanks, Al