Mystery Connector??

[JoeCanada]

I was replacing my lower intake gasket, and when I disconnected the wiring harness for the fuel injectors, et al, I discovered the following (see pic).

There are four wires: Blue/Orange Stripe, Black/White Stripe, Grey/L. Blue Stripe and Orange. What are they for??

 

[94EXPLODER]

what year is that? i have a 94 exploder and just did the intake manifold gasket about a month ago i can check on mine to see what that goes too...

 

[JoeCanada]

Mine's a 94 4.0L. According to the Haynes manual, they appear to be for some O2 sensors. Does this make sense?

 

[MAKG]

Mine's a 94 4.0L. According to the Haynes manual, they appear to be for some O2 sensors. Does this make sense?

Not if it runs decently and the check engine light isn't on.

Those wires look crimped on. Definitely not stock.

 

[V8 Level II]

Mine's a 94 4.0L. According to the Haynes manual, they appear to be for some O2 sensors. Does this make sense?

Those are for the passenger side O2 sensor.

 

[JoeCanada]

The CEL does in fact come on after a few minutes of driving...perhaps this is why.

 

[V8 Level II]

The CEL does in fact come on after a few minutes of driving...perhaps this is why.

You can pull the code without a reader on a 94: http://www.troublecodes.net/Ford/

 

[JoeCanada]

It doesn't say anything pertaining to a 4.0 Ranger, does the same procedure still apply?

 

[V8 Level II]

That procedure is for EEC-IV like your 94 Ranger.

 

[JoeCanada]

OK, next question: Why are there four wires for the O2 sensor? I've only seen O2 sensors with one or two wires.

 

[V8 Level II]

OK, next question: Why are there four wires for the O2 sensor? I've only seen O2 sensors with one or two wires.

Signal - read by the PCM as a voltage representing the exhaust oxygen level
Signal return - dedicated ground back to PCM
Nominal 12v supply for sensor heater
Chassis ground for sensor heater

 

[MAKG]

Yup, it's a heated exhaust gas oxygen sensor. Most are these days. Even the older RBVs have three-wire sensors (signal is case-grounded). The dedicated ground is MUCH better than the older body/engine block ground solution.

 

[JoeCanada]

Problem solved!

Problem is solved. I found the connector for the O2 sensor dangling under the truck, so I attached a new male socket to the four wires above and connected the O2 sensor, and volia...no more Check Engine light. Apparently the computer didn't like running with one O2 sensor, go figure.

I tried to read the codes using the procedures described above and in the tech library, but I was having trouble reading exactly which codes it was throwing. Fortunately the solution was simple enough.