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Discussion Starter #1
I am restoring a '71 Chevelle SS 454 and I have three wires with a connector on the end that I don't know where it goes. It wasn't hooked up when I got the car. The three wires are blue, light green and tan (or light brown). The connector is a two prong connector that is (currently) located near the wiring gutter on the firewall. The blue and light green wires go to one prong and the tan (or light brown) wire goes to the other prong. I have a wiring diagram, but I cannot find this on the diagram. Is it possible that it is supposed to connect to a TCS solenoid? That's just a guess because the car doesn't currently have a TCS solenoid. Is it supposed to? I see that Year One sells the solenoid, but they don't list one for a '71 454. Sorry for taking so long to explain myself. Please help if you have any info!

Chad Oudekerk
 

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You're probably looking at the TCS connector. I bought a wiring diagram for my '71 Sprint, but couldn't make any sense out of it, so I had to buy the assembly manual. Turns out there are several different wiring plans for the car (ok, well, at least two!), and the first diagram I bought was (of course) not what I had.

Do you have one or two TCS relays on the firewall? Are the wires you're asking about long enough to reach the temp sending unit on the engine? Are you planning a full restore, or building a driver? The TCS stuff is pretty useless, unless you're trying to get back to original.

Good luck!

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Cecil Hawkins
San Diego, CA
1971 GMC Sprint
The Project
All I need is time...and some $$$
"Tourist, go home! And take someone with you!"
 

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Discussion Starter #3
Thanks for the info Cecil. I have two relays mounted on the firewall right above the distributor. They are the same size and shape, but they are slightly different relays. What are they for? The wires are long enough to reach the temp sensor. I am trying to restore the car as close to original as possible. However, I do have a HEI distributor. What does the TCS do exactly?
 

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I show that connector as part of the Air Conditioning Control. Used on an A/C equipped car. I don't have an A/C car but I think it originally went through the firewall. How does TCS work? IMO it doesn't. There is an explanation of how the system is supposed to work in the Chevelle Haynes manual available at the chain auto stores. The system is unreliable and parts are a pain to find for it. The relays are part of the TCS & A/C circuits.John_Muha
 

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Discussion Starter #5
My car has air conditioning and I'm trying to get that working too. Everything's there - I thought it was ready for refrigerant and it would work. I know the wires are not for the compressor motor, but they could be for something else - any idea what? Are you saying that the wires should be under the hood or inside the car?
 

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Check your email and see if that helps. I may be wrong on the connector but that's the closest thing I could find in that area.
 

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I don't have TCS info for a 71 only a 70 and it has one relay. TCS = Transmission control spark. It was intended to reduce emissions by removing vacuum advance under certain conditions. The components are: Override relay, Vacuum control solenoid, temp override switch(2 prong temp sender) and transmission switch.

For temps under 82deg or over 232 deg the temp override switch (2 prong temp sender in passenger side head) provides a ground to the override relay which disables the vacuum control solenoid and allows full vacuum to the distributor.
For temps between 82 and 232 12v is applied to one side of the vacuum control solenoid. The transmission switch provides the ground in 1st & 2nd gear only. So you have no vacuum advance until the tranny switches to high gear then you have full advance.

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Steve Strasemeier (70SS 396, Fathom Blue/White Stripes)
My 70SS
 

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The plug in question is indeed part of the A/C wiring. It connects to a temp switch that is installed in the evap housing. It is on the right-hand side directly under the suction throttle (POA) valve. This switch will stop the compressor (interrupt the power to the clutch) on low blower discharge temp (around 32 Deg F). The green wire goes to the comp clutch. The tan wire comes from the A/C switch at the controls. The blue wire comes from the anti dieseling relays behind the glove box.
 

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Discussion Starter #9
Thanks for the information Elree. Do you know how hard it is to get to the temp switch? Do I have to take the evaporator housing apart to get to it? I assume the evaporator housing is the big unit that attaches to the firewall - correct?
 

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It turns out thet the plug and wires in question do not connect to the temp switch. The 71 A/C harness that I have has two wires for the temp switch, a light blue and a dark green. At this time I don't know what the wiring is for.
 

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Well stumping a lot of people. Maybe Cecil is right but I can't match that connector up to anything I can find. Maybe see where the other ends of the wires go to (if you can)and someone will have an idea.
 

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You rang?



Hmmm, guys I've got to admit, I'm a bit stumpped as well. It smells suspiciously T.C.S. system to me. Try measuring the TAN wire (with respect to chassis ground) when the engine is running (or with the key in the "ON" position). If it's "hot" with 12v, I'm pretty confident it is T.C.S. related.

P.S. John Muha, I haven't forgot about the 1-wire idiot lite circuit, just been "backlogged"...Man I hate winter.
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by Coppertop:

P.S. John Muha...Man I hate winter.
<HR></BLOCKQUOTE>
Know what you mean. Ain't it a bear wearing that sweater in the evening. Take care Joe.
 
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