Mystery Wire??

[O-Ring]

While I was crawling around on the motor removing injector connections (’93 F350 7.3, early Banks Sidewinder), my clothing pulled off a wire and I don’t know where it goes. The clue is that it is the red/white striped wire coming from the direction of the firewall (yellow arrow) in the loom serving the glow plug relay. The wire runs a good 2.5 feet once it leaves the loom just below the yellow arrow (with several splices done by PO) – it does NOT connect to the relay and it terminates in a round push on connector (white arrow). If I knew what the red/white striped wire is supposed to connect to, I’d sleep a lot better. Any help very much appreciated. Merry Christmas!

 

[IDIBRONCO]

I just double checked this on my 1985 F250 and, going off of it, I'm going to guess that it's for the factory oil pressure sender. I think that wire was kind of universally used for the oil pressure sender. I don't know what your set up is like or remember if it works. You can check to see if my guess was right or wrong.

 

[Big Bart]

That style of slide on connector is generally for a sending unit (Water temp, oil, etc.) or starter solenoid. Could be for a stock or aftermarket sending unit.

How to test.
1) Ground it and see if one of your gauges pegs, if yes you found it.
2) If for the starter it will have +12v with the key in the start position.
3) If for a aftermarket glow plug solenoid (The one in your picture is the stock 7.3 style.) it will have 12v briefly when you turn the key to on or via a switch installed in the truck.

Also I would do a proper repair and get rid of the 3 way splice connector. Use a néw connector or solder and shrink wrap the, together.

Let us know what you find out.

 

[Noiseydiesel]

First check it for voltage before grounding it out looking for a gauge needle to move.
As was stated, eliminate the splices.

 

[franklin2]

Here it is in this diagram. Coolant sensor is red/white. Oil pressure is white/red.

 

[O-Ring]

All of this is feedback is super helpful and I will report back. Will check it out today. Thanks!

 

[O-Ring]

Again, the advice (and the diagram) really helped! It turns out that the mystery wire goes to the old oil pressure idiot gauge. I didn’t install the calibrated aftermarket gauge now sitting on the dash, so it was not an obvious conclusion for me without the feedback. Thanks again and Happy New Year!

 

[IDIBRONCO]

I just double checked this on my 1985 F250 and, going off of it, I'm going to guess that it's for the factory oil pressure sender. I think that wire was kind of universally used for the oil pressure sender.

It turns out that the mystery wire goes to the old oil pressure idiot gauge.