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What did I get myself into?

4K views 23 replies 10 participants last post by  Avalanche 
#1 ·
When we bought our '71 it came equipped with a Ford solenoid on the firewall. I've wanted to clean the wiring up under the hood since then. I did a lot of research before starting the clean up. It looked fairly simple until I started stripping the tape off and see the "mess" now I'm not sure if it was a good idea. So far I've found 11 wires that go nowhere, I've got a horn relay attached to the firewall with wires attached to it that I'm not sure are supposed to be there. There are 4 wires where the horn relay is supposed to be that are terminated with butt connectors. I've got wires that are attached together with 2 terminal connectors and a bolt. I'm using a wiring diagram but it isn't as useful as I need at this point. I took some pictures today hoping someone could provide a little guidance, they were taken with my Playbook so they aren't the greatest quality.
 

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#2 ·
Hi Don.
It looks like somebody used a Camaro (later model) wiring harness to do some creative wiring. From where you are at, I would buy the 2 new underhood harnesses and redo what you have, That will save you an immeasurable amount of GRIEF.
 
#7 ·
Hi Don.
It looks like somebody used a Camaro (later model) wiring harness to do some creative wiring. From where you are at, I would buy the 2 new underhood harnesses and redo what you have, That will save you an immeasurable amount of GRIEF.
I'm thinking your right about the new harnesses. Any suggestions? Which 2 are you referring to? As you can see I can't go by my example.

First of all, the horn relay does not belong on the firewall in 71, that started in 72.
Looks to me like maybe someone relocated the horn relay for some reason and used butt connectors as wire splices to extend the horn relay wires to extend back to the new horn relay location. I guess, WHY? is the question.

In 71, the main power feed wire came from a pigtail on the positive battery cable as a main fusible link and went from there to a threaded terminal post behind the right side headlight, then onto the BAT terminal of the horn relay which was behind the left side headlight.

In 72 the main power feed wire went on the starter post along with the positive battery cable as a main fusible link and went from there to the horn relay on the firewall near the master cylinder.
That was my reaction "WHY?". I knew a long time ago it was supposed to be on the rad cradle. That was going to be one of the things I was going to relocate. I'm trying to picture your description of the wiring for the horn relay but I can't, a picture might help if there is one

Not wanting to be a smat alec, but I agree with Levon. Buy a new under hood set and junk all that. Unless you can get the guy who did that explain it to you. Even then ,for looks alone I'd change it.
I would ask the guy who did the wiring but he's kinda dead. The guy I bought the car from bought it while the guy was in the hospital. He had a terminal illness, was in a wheel chair while working on the car, I think that's why the Ford solenoid. He probably used it to bump start.

Oh...


The bulkhead connector is the engine compartment side of the fuse box.
Didn't think it was the bulkhead connector, but with this car nothing is what it's supposed to be. I thought a bulkhead connector was like a distribution block? My mistake.
 
#3 ·
First of all, the horn relay does not belong on the firewall in 71, that started in 72.
Looks to me like maybe someone relocated the horn relay for some reason and used butt connectors as wire splices to extend the horn relay wires to extend back to the new horn relay location. I guess, WHY? is the question.

In 71, the main power feed wire came from a pigtail on the positive battery cable as a main fusible link and went from there to a threaded terminal post behind the right side headlight, then onto the BAT terminal of the horn relay which was behind the left side headlight.

In 72 the main power feed wire went on the starter post along with the positive battery cable as a main fusible link and went from there to the horn relay on the firewall near the master cylinder.
 
#8 ·
IIRC there are 2 harnesses that come from the bulkhead connector on the firewall. 1 is for forward lamps and 1 is for the engine. These are the 2 I would replace. American Auto Wire builds good stuff.

It may look like a big job but you can do it in a day if you have help and a good wiring diagram.
 
#12 ·
IIRC there are 2 harnesses that come from the bulkhead connector on the firewall. 1 is for forward lamps and 1 is for the engine. These are the 2 I would replace. American Auto Wire builds good stuff.
X2 I'm thinking that would be your best bet and you will have the cleanest look too!
 
#10 ·
Just to add...

The new harnesses can be ordered with changes intergrated to include things like a HEI distributor or an internal regulated alternator.
AAW or M&H are both great suppliers and can be ordered directly or from any Chevelle parts vendor.
 
#11 ·
Thanks Bill.
I ordered the AAW harness today from "Antique Chev" near Dundas Ontario. It should be here in a week and a half to two weeks. The wife and I were going out for the day and there was another part I needed so we drove to AC and carried on from there.

P.S. They are shipping it to me for an extra $15.00. I can't drive there and back for less (even in my VW Golf TDI).
 
#13 ·
Got my harness this past Thursday after waiting 4 weeks. I proceeded to install the engine harness but there are some questions. There are no instructions included withe the harness, I checked the AAW website and it says one is not available because your supposed to use the existing one when installing the new harness (not so in this case). Nothing about the new one is the same as the new one except some of the colours of the wires.

My questions are:
1) On the new harness, it appears (if I'm reading the schematic properly) the wiper connections are on the harness, whereas the old wiring harness the wiper connections are on the right side bulk connector or the same side as the lights, which is correct? If this is wrong then I might have '72 wiring in my car. If not and the harness is right, will the wipers work if the wires are coming from the new harness? (I'm thinking NO)

2) Is a '71 harness the same as a '72 for wiper connections or anything else?

3) There is one extra wire coming from the bulk connector on the old wiring It's black and was connected to the horn relay, it's on the bulk connector on the top right as you look at it from the front of the car. Any idea what it's for?

4) What are the CEC Rev Rly and the Time Delay Rly as specified on the schematic I got from this site. (I've been using this to get an idea where things are supposed to go)

I hope this is clearer than mud. I'm pretty frustrated at this point because nothing has been working out as easily as things appear. I'm going to contact AAW to see if they can help with some of these questions, I thought I would ask you guys to see if I could get an answer that makes sense.
 
#14 ·
Hi Don.
Do you have the wiring diagram(s) It is sooooo much easier with them.

www.Classiccarwiring.com does some great ones in colour.

Otherwise it may be a pain trying to explain some of this. Post pictures as you go and that will help with the explanations that you are seeking.
 
#16 ·
Hi Don.
Do you have the wiring diagram(s) It is sooooo much easier with them.

www.Classiccarwiring.com does some great ones in colour.

Otherwise it may be a pain trying to explain some of this. Post pictures as you go and that will help with the explanations that you are seeking.

Levon
Thanks but I don't have that particular diagram, the one I have is from "Peach State Chevelles" web site. I just had a look at the one they have on their site for the '72's and it matches the one in my car. The wiper connections are on the other half of the bulk connector. I guess I'll have to send this one back and get one for a '72. What a piss off!!!


I believe the tip-off of whether you have a '71 harness or '72 harness (dash harness that is)...is the wiper switch.

The 1971 harness is like the '70's....the wiper switch has the dark blue, the black, and the light blue apart of the plug.

The 1972 has an integrated ground that is offset from the main three terminals mentioned above. So it has a 4 terminal plug.........
Coppertop
Thanks for the pointer but as you can see in my response to Levon I found out which one I have.
 
#15 ·
I believe the tip-off of whether you have a '71 harness or '72 harness (dash harness that is)...is the wiper switch.

The 1971 harness is like the '70's....the wiper switch has the dark blue, the black, and the light blue apart of the plug.

The 1972 has an integrated ground that is offset from the main three terminals mentioned above. So it has a 4 terminal plug.........
 
#17 ·
NOTE: Your car is a 71:yes: with A/C, NOT a 72.:noway: You have TWO relays under your glove box, What do they do???? When you shut the key off, One of the relays sends power to the A/C clutch for a short time. WHY??
This my friend was the " New and Improved Anti Dieseling System " for 1971.
When you are all done with your wiring try this. With the engine running ( In a quiet place) Turn the Ign. OFF and pull the key out of the column. NOW LISTEN........ You will hear a CLICK,, The A/C clutch has just engaged, ( This puts an extra load on the engine, So it will not DIESEL )
KEEP QUIET and LISTEN ! WHY?--- In a few seconds you will hear another CLICK, Whats That??? --Its the timer relay shutting the power off to the A/C Clutch. Remember all of this is done when the KEY is in your hand and not in the IGN.
Bob
 
#18 ·
The wiper wires are part of the engine harness on the 71, not the forward lamp (light) harness. Sounds like you unknowingly might have started a complete rewiring of your whole car. :(

Edit... Sorry, I didn't see the last two posts before posting this.
 
#20 ·
Post a picture of your new harness and the plugs. There are relays on the firewall with these cars. One is for the TCS (Transmission controlled spark) and it uses 2 plugs. 1 at the firewall and 1 at the pass side front of the engine. Maybe that is what you are seeing???
 
#21 ·
NOTE:
The 71 A/C harness----- It is a stand alone harness. It has nothing to do with the under dash or under hood harness.
As always, Some times they get hacked into by someone looking for a " HOT WIRE ". This is another problem to deal with.
Bob
 
#23 ·
OK.
Have a great week.
 
#24 ·
It's been a while since I've posted. I went back to my old harness and started from scratch. I used the wiring diagram I have and traced everything I needed and eliminated the wires not needed (after everything was working correctly). I left the horn relay on the firewall because it worked out better for me. I know it's not correct but it seemed much easier than extending more wires to the rad support. I hid most of the wiring behind the engine rather than up on the firewall for a bit of a cleaner look. Now all I have to do is reinstall my MSD and Tach Adapter and it should be good but that can wait for a later time as I have a Pertronix Flame Thrower distributor in the mean time. I'll post a few pics later.

Oh yeah the vendor I got my AAW wiring harness from wouldn't take it back as it was a special order, so if anyone needs a '71 engine wiring harness I have one for sale.
 
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