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Fox Mustang - 4th wire in O2 Sensor Harness?


twistedfocus1647545489

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So, trying to diagnose my rich/surge idle condition and I'm down to O2 sensors. While changing them out today I noticed an old splice in the signal wire on the driver's side (short red wire). No biggie, I'm guessing this once was wired to an A/F gauge.... But...

 

I found what looks like a fusible link in the same harness that was just balled up and zip tied to the rest of the harness. Both O2's are 3-wire on these cars.I have no fucking clue what this should be attached to, but I would guess it is supposed to be attached to something. I almost wonder if it was spliced into that signal wire, but why the fuck? Maybe something to do with the Mass-air conversion? This is a MAF converted 88.

 

tl;dr - Anyone have any idea what the hell the 4th wire in the driver's side O2 Harness is supposed to hook up to? Does it even belong there? It looks factory-ish to me based on the way it's wrapped futher up in the harness with the factory fabric shit.

 

Strange 4th wire is the long one on the right:

http://img.photobucket.com/albums/v691/twistedfocus/JasoniPhonePics6-21-11001.jpg?t=1318696464

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Sure it doesn't connect to something close to where the O2s are? I don't know these cars at all so I'm curious.

I thought that, but there's not really anything else around there that I'm aware of. Maybe the reverse lights on the trans.

 

Come to think of it, this car has longtubes, so maybe if the O2s were in the factory position (nearer the engine bay) they would be near something it could go to. I'll have to investigate that further. It seems really long though if that were the case.

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Update: poking around online I found a diagram that indicates that the low-oil level sender wire is routed thorugh this section of the harness. That's at the back of the oil pan, so that may very well be it. Headed back to the garage to find out.
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I don't know dick about mustang wiring, but on my cars, they all run 4 wire 02's.

 

2 wires are for the sensor itself (output& gnd) and the other 2 are for the sensor heater to get the sensor up to operating temp faster.

 

I can theoretically see a vin split where ford started using a 4 wire heated sensor vs not perhaps ?

 

 

 

In looking at the picture though, Cordell would be spot in, given it has it's own separate wire (that would appear to be something that would plug into a typical 1 wire oil sender) it's likely just taped together.

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Well, the low oil sender is absent from this pan, which appears to be a replacement. Looks like a pretty prime contender for being the wire to the now gone sender. I feel a bit better about it now.

 

Thanks all for helping think through it out loud.

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Well, the low oil sender is absent from this pan, which appears to be a replacement. Looks like a pretty prime contender for being the wire to the now gone sender. I feel a bit better about it now.

 

Thanks all for helping think through it out loud.

 

For some reason the picture didn't load for my iPad the first time. That is the low oil sensor wire for the dash light for the side of the pan.

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