What is this harness and where does it go? - Page 2 - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #16 of 19 (permalink) Old Dec 25th, 12, 7:12 PM Thread Starter
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Re: What is this harness and where does it go?

Levon - thank you for your quick response..Sorry for my delay but still at work...

Here is the anomalies in my wiring thus far...

1. Yellow ( from starter Solenoid I think) goes to a wirenut that is connected to a Red wire running from the HEI Distributor and connected to nothing. There is also another red wire from the engine fuse connector that also connects to this wirenut. (according to my diagram- the yellow goes from the starter solenoid to the coil. I dont have a wire diagram with the HEI in it. I cannot find a Red wire anywhere on my diagram).

TCS Delay Relay - (i have been told that I dont need this)
1. Lt Green goes from TCS Delay to a dead end bundle ( Ill call dead end bundle #2 - This bundle is just lying behind the master cylinder booster connected to nothing)my diagram shows this going to a TCS solenoid??)
2. Tan from TCS Delay to Dead end bundle #2 (diagram shows it splice to tan from TCS Solenoid then to engine fuse panel).
3. Black from TCS delay to Starter Solenoid ( i think)(diagram shows it going to trans switch connector)( if i dont use this - where does this black wire go?)

TCS Reversing Relay - (i have been told that I dont need this)
4. Dk Blue from TCS Reverse to Dead End bundle # 2 (diagram shows going to TCS solenoid)
-there is also a dark green and a brown coming from this to the engine fuse panel. If I dont use this - where will I connect them from the engine fuse panel to ??)

5. Black from AC Relay to Starter i think (diagram shows it going to blower motor??) (Sorry I dont know where the blower motor is located but it appears to go to the area where the starter is located)
6. Dk Blue fused to Purple from AC resistor to Starter Solenoid.(diagram shows it going to the AC relay switch)

The wiring diagrams that I have been referring to are the following:
A) Chevy Chassis Service manual for Chevelle/El Camino - Engine Compartment - Chevrolet Fig 80
B) 1971 Chevy Chevelle Wire diagram from this forum (http://www.peachstatechevelles.com/c...=236&cat_id=-1)
C) Assembly Manual for Chevelle "air conditioning - Wiring Diagram V8 - Sheet 12H-3

I have sweep dash with idiot lights...

Thanks again for helping me with this....
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post #17 of 19 (permalink) Old Dec 26th, 12, 10:15 AM
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Tom Terrific II
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Re: What is this harness and where does it go?

If you have an HEI tell AAW. they will eliminate that yellow wire. It's used to bypass the resistor wire for full batt voltage during cranking. If you have an HEI you don't need it, it will be full batt voltage all the time. AAW can eliminate the resistor wire. It's used for points ignition, not needed or wanted with HEI. BTW, you won't find a wire diagram with HEI, they didn't come out till 74-75.

TCS, it's not Delay, it's Relay. There is no Engine fuse, are you talking about the IGN spade terminal? It's not fused AFAIK. It's where the HEI could be connected if you don't ask AAW for an HEI type harness. Ask AAW to eliminate the TCS wiring, the solenoid is probably gone and not worth replacing unless you're doing a 100 point restore.
All it did was cut off the vacuum advance while the engine was cold, supposedly helped it warm up faster. It was controlled by a pressure switch on the front right of the tranny if it was a TH 350. Eliminate if possible.

TCS reversing relay? not familiar with this, sure it wasn't part of the reverse lights?

5. Hi-blo relay, supplies direct battery current to blower motor when A/C is fan is on Hi. On the cars I've worked the big wire comes from the junction block, buss bar on the horn relay, runs down the left fenderwell, across the firewall in the plastic wire gutter. the fuse is inline at the passenger side of the wire gutter. goes to the Hi-Blo relay which is controlled by the fan switch in the dash. From the relay it goes to the fan located in the right side of the firewall behind the inner fender. Sounds like it's possible somebody tried to eliminate/bypass the long wire from the horn relay by attaching to the battery cable post on the starter? Be careful here, there's big purple wire from the ignition switch to the inside small post on the starter, that's what makes the starter start.

That yellow wire running from the starter to the coil would have been attached to the outside small post on the starter.

Dk Grn/Brn, what color are the wires to the wiper motor? Are they in place? I can't remember what color they're supposed to be.

If the car is not already changed over to to the 10SI type alternator with internal regulator this would be a good time to do it. AAW can modify the harness to eliminate the the old style external voltage regulator mounted on the back side of the core support near the horn relay. The ALT idiot light on the dash will still work right.

I'd get the engine and front lights harnesses from AAW with the mods mentioned. For some reason IIRC the long wire from the horn relay to the Hi blo relay is separate. Ask for it, the old fuse holder is probably melted anyway. Common problem on these cars.

Got all that clear as mud? Good.

Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife.
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post #18 of 19 (permalink) Old Dec 26th, 12, 1:01 PM
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Re: What is this harness and where does it go?

HI Jeff.
As soon as you said wire nut I cringed. THis usually indicates a "low bidder install" . With all the bad wiring and what you need fixed plus what you do not see, I would replace the engine, lighting and AC harnesses. It may sound expensive but will be more reliable and eliminate a potential fire hazard going forward.

Like Tom says, get in touch with AAW and they will be able to help you. It will be well worth it, faster and safer.

Levon Hovagimian
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post #19 of 19 (permalink) Old Dec 26th, 12, 1:41 PM
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Re: What is this harness and where does it go?


The “TCS” system is different for each year 70, 71 and 72.

The 71 system is correctly called the Combination Emission Control system (CEC). It has two relays, a reversing relay and a delay relay. Also has a carburetor mounted (CEC) solenoid that has two functions: ports/blocks the distributor vacuum advance and sets engine idle.

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