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- Aug 8, 2018
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- California
- My Car
- 72 Fastback - 351C-4V, Fitech EFI, T56 Magnum 6 Speed
Hello, preparing for the end of the world so cleaning up the wiring in my '72 formerly auto non AC car and ordered this new feed cable to go from the firewall to the sensors.
https://www.cjponyparts.com/cj-classics-engine-gauge-feed-wiring-harness-usa-made-351c-1971/p/WGF6C/
My car has a 351C but didn't come with that originally and I didn't catch the difference before ordering. My current feed harness has 4 cables where this one only has 3. Of the 4 on the old harness 2 are actually cut off at the plug. The two remaining has one going to the oil pressure switch and the other powers the ignition. Not sure how that happened, but that's the way it is now. I have a wiring diagram, but not able to make sense of this.
I'm changing from lights to gauges so I replaced the sending units and figured I'd just restore the cabling to what it was and go from there. Looking at this closer, it looks like the wires work out if I just plug in the new 3 wire feed cable into the 4 wire connector with the power and oil pressure in the same locations.
Not sure if that is wise or not so figured I'd check here and find out how this should be working. I don't care if it's factory accurate, but I want it to work well. I also stuck a meter on the connector at the firewall and I'm getting switched 12V on 3 pins and ground on the 4th. So now I'm more confused as I didn't think there should be power going to the sending units.
Hope that makes sense. But basically are the cables on that 3 wire harness in the same locations if I plug into that 4 pin connector at the firewall? Is 12V going to the senders normal? Is that where the ignition usually get's it's power?
And for bonus points, right next to that 4 pin connector at the firewall, there is a 2 pin connector hanging at the firewall that has switched 12V. Anyone know what this is for?
Thanks as always for any help figuring this out.
https://www.cjponyparts.com/cj-classics-engine-gauge-feed-wiring-harness-usa-made-351c-1971/p/WGF6C/
My car has a 351C but didn't come with that originally and I didn't catch the difference before ordering. My current feed harness has 4 cables where this one only has 3. Of the 4 on the old harness 2 are actually cut off at the plug. The two remaining has one going to the oil pressure switch and the other powers the ignition. Not sure how that happened, but that's the way it is now. I have a wiring diagram, but not able to make sense of this.
I'm changing from lights to gauges so I replaced the sending units and figured I'd just restore the cabling to what it was and go from there. Looking at this closer, it looks like the wires work out if I just plug in the new 3 wire feed cable into the 4 wire connector with the power and oil pressure in the same locations.
Not sure if that is wise or not so figured I'd check here and find out how this should be working. I don't care if it's factory accurate, but I want it to work well. I also stuck a meter on the connector at the firewall and I'm getting switched 12V on 3 pins and ground on the 4th. So now I'm more confused as I didn't think there should be power going to the sending units.
Hope that makes sense. But basically are the cables on that 3 wire harness in the same locations if I plug into that 4 pin connector at the firewall? Is 12V going to the senders normal? Is that where the ignition usually get's it's power?
And for bonus points, right next to that 4 pin connector at the firewall, there is a 2 pin connector hanging at the firewall that has switched 12V. Anyone know what this is for?
Thanks as always for any help figuring this out.
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