73/74 torino engine wiring harness compatible?

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   Ive got a 351C that requires the 74 engine wiring so it can plug into the ignition module. However, my torino is a 73, with the matching 73 dash wiring harness. How compatible are the two harnesses? I know the wiring diagrams are different, but so far ive been able to get the car running with no modification.
I have been restoring the car, however, and do have other electrical issues. Turn signals not working, hazards not working, brake lights not working, heater motor not working, and dome light coming on randomly when i make a left turn. That all sounds to me like grounding issues, so ive got the whole dash out to clean all grounds. 

If anyone has any insight on what the difference between this years wiring harnesses are, let me know. I will update once i reinstall the dash with fresh ground points. 

Thank you!

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LiamGranTorino Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 18-February-2026 Location: Oregon Status: Offline Points: 5	Post Options Post Reply Quote LiamGranTorino Report Post Thanks(0) Quote Reply Topic: 73/74 torino engine wiring harness compatible? Posted: 18-February-2026 at 7:50PM
	Ive got a 351C that requires the 74 engine wiring so it can plug into the ignition module. However, my torino is a 73, with the matching 73 dash wiring harness. How compatible are the two harnesses? I know the wiring diagrams are different, but so far ive been able to get the car running with no modification. I have been restoring the car, however, and do have other electrical issues. Turn signals not working, hazards not working, brake lights not working, heater motor not working, and dome light coming on randomly when i make a left turn. That all sounds to me like grounding issues, so ive got the whole dash out to clean all grounds. If anyone has any insight on what the difference between this years wiring harnesses are, let me know. I will update once i reinstall the dash with fresh ground points. Thank you!

LiamGranTorino Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 18-February-2026 Location: Oregon Status: Offline Points: 5	Post Options Post Reply Quote LiamGranTorino Report Post Thanks(0) Quote Reply Posted: 20-February-2026 at 8:23PM
	Okay, so i reinstalled the dash with cleaned, perfect grounding points. Checked with multimeter, and theres 0 ohms. So the grounds are definitley clean. Tried it, and the turn signal worked for a few seconds. The heater worked for a few minutes, The hazards didnt work at all. the seatbelt buzzer works still. The key buzzer worked for a few seconds, but quickly stopped working. The footswitch dimmer works, the oil light is on when key is on. Then i tried running a jumper wire directly from the battery, to the ignition fuse, nothing changed other than the thing being on when the key wasnt turned. what the hell! I have a spare 73 harness that im going to wire in temporarily, just to see if it is the mismatched harnesses. If that is the case, ill just convert back to the points style distributor and live with it. Does anyone know how i can diagnose the issue? Has anyone else had this issue? Why would electronics work temporarily but crap out one by one over a period of time? Very confused, looking for someone thats had similar experience, or is knowledgable with wiring, as i am very much not. Thanks anyone that can help!

californiajohnny Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14723	Post Options Post Reply Quote californiajohnny Report Post Thanks(0) Quote Reply Posted: 20-February-2026 at 10:34PM
	most of the wiring should be the same wipers, lights, etc the duraspark box has 2 connectors that plug into the brain box 1 has the wires up to the coil usually a seperate small harness but a duraspark can be wired up to replace points fairly easily... the pirple and orange wires from the dist go to the brainbox plug some may have a 3rd black wire its a ground and may not be needed the power side has a white/red stripe wire and another red wire going into the brainbox that ign power i dont recall what the 3rd wire on that connect is to? the box grounds through the mounting screws on the fenderwell BTW
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