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#1 |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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What are these solonoid looking things on my firewall for??
Hey guys,
I was redoing my HEI distributor power wire this week and noticed a second bundle of wires running to my engine that were not connected to anything. The HEI power wire bundle ran together with all the starter wires but this second bundle came from these solonoid looking parts on my fire wall and went to my engine for some reason. I looked on the wiring diagrams but didn't have much luck, what are these wires for? Truck seems to run perfect without any of them hooked up..
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#2 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,917
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Re: What are these solonoid looking things on my firewall for??
TCS - transmission controlled spark. It was an early emissions device. You can safely delete it.
__________________
I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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#3 | |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Quote:
Out of curiosity, how did that emissions system work?
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#4 |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
FYI, found this on another forum..
The TCS system was there ONLY for EPA emissions purpose. It did NOTHING for the engine, for economy, or for performance. Basically, it retarded timing when the transmission (either manual or auto) was in lower ranges, but dropped out if the engine was either too hot or too cold and/or if WOT was employed. A retarded engine will run hotter in the combustion chamber and burn off more of the residual hydrocarbons.
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#5 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,917
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Re: What are these solonoid looking things on my firewall for??
I've only seen TCS systems with a single relay. Can you move the black wire loom so it's easier to see what's going on there?
__________________
I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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#6 |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Took some more pics from different angles for you, hope it helps!
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#7 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,432
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Re: What are these solonoid looking things on my firewall for??
The TCS relay has dark blue and dark green wires to it. The other item is not part of the TCS system.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#8 |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Dang, any idea where I could find out what the other relay is for? Wiring diagrams maybe? I'd really like to get rid of that whole second harness..they arent connected to anything right now
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#9 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,432
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Re: What are these solonoid looking things on my firewall for??
OK, Looking at this wiring diagram, that says (O2 only), if I'm reading it right. That's an 18 ga tan wire on it. Up near the top right it shows heater blower power (Except O2). I'm drawing a blank, maybe someone with more electrical knowledge can point you right. Does your heater blower work?
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#10 | |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Quote:
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1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) Last edited by Yamariv; 02-27-2023 at 08:17 PM. |
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#11 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,432
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Re: What are these solonoid looking things on my firewall for??
OK, I don't know what "O2" means. But it does seem to indicate some difference in the heater blower motor wiring. Many times when I get into the nitty-gritty details with things like this on the internet, it seems like I get it wrong, so I want someone with more experience to weigh in. If I had the truck in front of me, I'd be able to figure it out.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#12 | |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Quote:
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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#13 |
Registered User
Join Date: Oct 2022
Location: Regina, Saskatchewan
Posts: 343
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Re: What are these solonoid looking things on my firewall for??
Just a quick thread update.. I posted in the electrical section but didn't get any further info on the second solenoid so I decided to remove the whole harness and solenoid setup and see if the truck still runs. Yup, ran fine, both these solenoids can hit the junk pile incase someone is wondering about their truck. These are just for the TCS emissions system.
Engine bay looks much cleaner now and I only have one harness running to the engine. Woohoo
__________________
1971 Chev C10 - 250ci L6 w/3 speed on the floor Upgrades: Power Steering 3 Core Radiator 7 Hole Gauge Cluster Power Brakes (Incoming!!..) 1971 350 (Incoming!!..) |
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