Oil Pressure sending unit connection 68 XR7

Hi! Slowly but surely my 68 XR7 is coming back to life. My gauges don’t all work. A while ago I replaced the voltage regulator with a solid state from WCCC. My speedometer works, my temperature gauge works… In theory my fuel gauge works but I still haven’t put more than like 2 gallons in the tank so that’s harder to tell. My tach doesn’t work (another story)… but my oil pressure gauge doesnt work. I looked at the sending unit … and there’s no lead attached on the end at all (it’s a spade connector fwiw). And I can’t seem to find a lead for it coming out of the wiring harness anyplace. I assume it should have one and these didn’t talk to the gauges by magic. I tried to see it in the shop manual but honestly, I didn’t see it / couldnt figure out which schematic had it. Can anyone share with me where that darn wire is hiding or how I can run a new one from gauge to sender? thanks!

There is a three wire harness that connects to the Coil +, Temp and Oil sensors.

Welcome! Usually the wires run along the inside edge of the driver side rocker arm cover. A quick test of gauge function is to ground the wire to the sender and watch the gauge. It should go beyond the high point of the scale. Do not leave it like that long as you can fry the gauge.

Thanks for your answer. My dash to engine feed harness has a wire to the coil, and a wire to the temperature gauge … and a 3rd wire that’s solid red, not connected to anything but gives off about 9.2v . Could that be the oil pressure sending unit wire?

That’s odd,.

The wires should be:
Ignition - Red with a green stripe.
Temp - Red with a white stripe
Oil pressure - White with a red stripe

Another thing - 1967 XR-7 has a spade type connector on the OP sender. The 1968 OP sender has a #10 stud type connector. Sounds like you have a lot of issues.

thanks Royce. This Cougar is always angry with me :slight_smile: and for sure some wiring issues. There’s clearly been modification done to the dash to feed harness at some point (there are wire nutted wires abound). Perhaps I should just buy a proper harness and at least be able to see the correct wires. I just worry that if I fix this that something else will unravel …

That caught my eye immediately when I read the original thread. An oil pressure sending unit with a spade lead is typically a sending unit for an indicator lamp and not a gauge. As Royce indicates, there are some serious discrepancies here…

That’s not the case at all and it isn’t what I said or meant. The 1967 versions use a spade connection whether gage or idiot lamp.

Meanwhile the 1968 and later versions use a #10-32 stud either version.

That way the same wiring harness is used for either year…

And that is why I said “typically” the spade lead is for an indicator lamp sending unit.

Folks, I am extremely knowledgeable about Mustang wiring, and although there are differences between Mustang and Cougars, there are more similarities than differences. I try to be as careful as I can when responding to Cougar wiring and electrical systems.

Any one else here think Another Major F up when you see AMF? Probably and excellent part but …

Thanks everyone!

btw when I look at the AMF website (cool site btw) … I only can find this version New Engine Oil Pressure Switch Sender With Light for Ford Bronco 350 - PS149 … specs say it’s a fit for the 68 XR7 Cougar but for the idiot light version. I can’t find the part @Royce that you shared for the full gauge flavor. Do you have the link for that?

OP sender 1968 XR-7

Thanks Royce. the ebay compatibility gizmo says its for 73 on up for the link you shared… is that correct/compatible?

Should be the same sender for 1968 - 89 Cougar with gage. Here’s another one:


I think you need to look at the 1967 / 68 Mustang harnesses. When you do you will find the situation is identical to Cougar, as are the senders for the oil pressure. Totally different harnesses and senders for 1967.

Oil Pressure sending unit connection 68 XR7 - #11 by Midlife

hi! Just thought I’d circle back … I installed the proper sending unit … and also ordered the proper harness. probably don’t need the harness now … but since I got it I might as well. In the interim I used my not so proper harness, connected the mystery 9.6v lead to the new unit and poof the gauge came to life and started to report pressure readings! So far I have the temp gauge working, the speedometer … now the oil pressure gauge but alas no tachometer yet. Car runs so I wonder if someone just bypassed it along the line. Where should the lead connect in the engine bay?