250 wiring question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Wildwagonz · 12-18-2013, 10:40 PM

I recently acquired a 72 c10 Longbed 3OTT with no engine. The truck was originally a 250 so I found a running 250 from a 67 and put that in. I'm trying to hook up the harness and I have a few that don't seem to have a home. These don't appear on the generic 67-72 wiring diagrams and I can't seem to locate a 72 specific diagram. I was hoping someone could give me a direction.
The harness coming off the bulkhead has 3 legs. One runs down the belhousing to the starter and oil pressure switch. No brainer. Second runs along the passenger side of the valve cover adn around to the coolant temp sensor, but there is another wire that's positioned as if it goes to the carb(Picture 1). Electric choke maybe? But the big mystery is a third leg that clips to the second and runs along the valve cover but has a single terminla connector and a dual terminal connector(Pciture 2)

Also, the third leg has a black wire at the back of the valve cover that has been snipped off. Any help would be greatly appreciated.

**'68OrangeSunshine** · 12-18-2013, 10:59 PM

Looks like it could be a later-model alternator [SI] connector. Or a TCS [Terminal Controlled Spark] smog-related connection they had on '71s and '72s?
Not sure at all. If you shift this Q to the Electrical page, member Vette Vet would probably know, for sure.

88Ironduke · 12-18-2013, 11:11 PM

Agreed that it looks like the TCS circuit. My 72 "had" it but it has since been removed. Good to see another 72' in New Jersey.

88Ironduke

Wildwagonz · 12-18-2013, 11:16 PM

Thanks. I thought it might be emissions related. That gives
something to look into

**'68OrangeSunshine** · 12-19-2013, 09:52 PM

Are you required to restore it as per your state's air quality regulations, or can you delete it? I would leave it out if legally possible. In California, the DMV requires all that archaic smog stuff to be onboard and working. Even if it did little at all for real air quality and was just a legislative band-aid. In Arizona, you can delete it, but all vehicles '67-and-newer are required to pass emission standards by the MVD.

Wildwagonz · 12-19-2013, 11:17 PM

I dont have any of the hardware so i just removed the harness and relay. New Jersey dorsnt realy care about emissions equiptment except catalytic converters. If it had a cat from the factoru it had to have it for emissions insoection so deleting it is no problem

12-18-2013, 10:40 PM	#1
Wildwagonz Registered User Join Date: Sep 2013 Location: Browns Mills, NJ Posts: 11	250 wiring question I recently acquired a 72 c10 Longbed 3OTT with no engine. The truck was originally a 250 so I found a running 250 from a 67 and put that in. I'm trying to hook up the harness and I have a few that don't seem to have a home. These don't appear on the generic 67-72 wiring diagrams and I can't seem to locate a 72 specific diagram. I was hoping someone could give me a direction. The harness coming off the bulkhead has 3 legs. One runs down the belhousing to the starter and oil pressure switch. No brainer. Second runs along the passenger side of the valve cover adn around to the coolant temp sensor, but there is another wire that's positioned as if it goes to the carb(Picture 1). Electric choke maybe? But the big mystery is a third leg that clips to the second and runs along the valve cover but has a single terminla connector and a dual terminal connector(Pciture 2) Also, the third leg has a black wire at the back of the valve cover that has been snipped off. Any help would be greatly appreciated.

12-18-2013, 10:59 PM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,441	Re: 250 wiring question Looks like it could be a later-model alternator [SI] connector. Or a TCS [Terminal Controlled Spark] smog-related connection they had on '71s and '72s? Not sure at all. If you shift this Q to the Electrical page, member Vette Vet would probably know, for sure. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

12-18-2013, 11:11 PM	#3
88Ironduke Registered User Join Date: Jul 2010 Location: Willingboro, NJ Posts: 489	Re: 250 wiring question Agreed that it looks like the TCS circuit. My 72 "had" it but it has since been removed. Good to see another 72' in New Jersey. 88Ironduke __________________ Retired USAF - No rockets, no mortars, no bad guys shooting...No stress!!! My Build Thread: Project 72' Green http://67-72chevytrucks.com/vboard/s...d.php?t=587932

12-18-2013, 11:16 PM	#4
Wildwagonz Registered User Join Date: Sep 2013 Location: Browns Mills, NJ Posts: 11	Re: 250 wiring question Thanks. I thought it might be emissions related. That gives something to look into

12-19-2013, 09:52 PM	#5
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,441	Re: 250 wiring question Are you required to restore it as per your state's air quality regulations, or can you delete it? I would leave it out if legally possible. In California, the DMV requires all that archaic smog stuff to be onboard and working. Even if it did little at all for real air quality and was just a legislative band-aid. In Arizona, you can delete it, but all vehicles '67-and-newer are required to pass emission standards by the MVD. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

12-19-2013, 11:17 PM	#6
Wildwagonz Registered User Join Date: Sep 2013 Location: Browns Mills, NJ Posts: 11	Re: 250 wiring question I dont have any of the hardware so i just removed the harness and relay. New Jersey dorsnt realy care about emissions equiptment except catalytic converters. If it had a cat from the factoru it had to have it for emissions insoection so deleting it is no problem



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