Electrical Signal return /reference wire.

Hey ! How are you all? I have a quick question about the reference wire on my 90 mustang ,5.0.
Does anyone know if the signal return wire continued thru the grey 8 pin or black 8 pin wire leading from ECU to sensors ? It's either Blk / wt or grey/ red. On this new used harness the grey only has five wires on the injector harness wires. The thing might need to be repin it. Thanks ahead for any info on the ref wire. I'll be checking the continuity today.
 
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I think that is a hard question to understand. Worded poorly, I guess the question is what color wires do I need in the two 8 pin connecters on a 90 five litre mustang..it's only got five wires coming out of the grey connecter. And seven out of the black.one. it may run but there aren't the same amount coming out to injecter harness.
 
Sounds like you are talking about the oxygen sensor harness jumper.

5-wire O2 harness sounds like you have a 1987 harness which was one year only. Really all you are missing is the jumper between 3 wires on the engine side of the harness that jumps out 2 of those 3 wires. You can certainly add it, or get an 89-93 harness and repin it.

Which wires get jumped all depend on if the car is an auto or manual trans and what ECU is in the car


Is this the harness you are referring to?