When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Backtracking a bit, the '71 convertible I bought was most disassembled by the previous owner. Sadly, he passed in the middle of the project and there are no notes or markings to be found on the car when I purchased the car. Not insurmountable, but a challenge.
I believe the engine and light harnesses seems to be in good condition just needing some cleaning. But I have this large guage wire coming from the horn relay (through a fuse holder...) and winding around the firewall alongside the harness and ending in a spade connector on the passenger side of the engine bay where it's spliced with another lead that comes out of the harness. I just ordered an elarged wiring diagram (www.classiccarwiring.com) that will hopefully help me identify the unmarked leads, but the owner-added lead has me concerned. Is the embedded wire in the harness suspect?...and this was a work-around? Where do the 2 spade terminals go?...
I think that you will find that the Orange wire from the relay goes to a relay that should be mounted on the Heater/AC box. The fuse should be 30Amp and the reason for the relay is so that they didn't put all that current through the dash switch. There should be a resistor assembly mounted into the evaporator box that is used to control fan speeds. Here is a PDF that I modified from the GM drawings that hopefully will help you. It says 1969, but there were almost no changes in this circuitry for several years. I think you will find if you look at most wiring diagrams that they will not show this because AC was an option and GM usually did not include them in their diagrams. If you look in most wiring diagrams you will find an orange wire to the heater blower, but it comes from the bulkhead connector. The wire on the blower on an AC car is a kind of purple wire from the relay.
Thanks for the guidance and wiring diagram. Big help. Mine is an A/C car.
So, being that A/C was optional and not included in the diagrams, is it safe to assume that the orange wire running outside the harness is correct, and added to the already built harness during assembly? On my car (as you can see in the pic) it is retained by zip ties that seem 'added'.
There is a 30 amp fuse in the holder. Resistor is there atop the box.
I'm not seeing a relay mounted to my box. I'm guessing it went missing and should be mounted in the circle? (A guy on eBay thinks they're made of platinum and asking $200 for one!!)
I am also missing a part on the side of the evaporator box (circled). Not sure what goes here?
The Red oval is the Resistors and the silver box is the relay. For some reason my AC box only had one screw hole and with the engine installed I can't drill another one.
You don't have the large gold colored cylinder as that was only 68 and 69. You should have the two pie pan vacuum unit.
The one hole in the side might be the Thermal Switch, but I have no idea what the other is. My car has louvers in the side and I really can't see into that area.
My drawing shows dark green and tan as the wire colors, but for your year they might have changed them to dark green and light blue.
After all the years that I have had my car I never thought about where the Thermal Switch was.
The resistors are nichrome wire and being in the AC box keeps air moving on them to keep them from overheating.
With a big block installed there isn't much room to work in that area.
Not much room? More like no room.
Upon further research, the ambient temperature switch is on the side of the evaporator box and no longer available The second hole with one mounting bolt is for a blower motor vent tube that serves to cool the blower motor with air from the box. Of course, my tube is missing along with the mount on the box that accepts the tube. Again, no longer available.
I've just found www.thepartsguy.com that offers rebuild/restoration and used/tested parts.
Thanks for all the help.
Bob
There is much more room to work on the driver's side. I can actually replace the spark plugs fairly easily. On the passenger side because of the AC compressor, I replace plugs 2 & 4 taking the front wheel off and going through the wheel well.
I forgot about the tube to blower motor. They only use it on AC cars, but I would think it a good idea for all cars. I changed the impellor on my blower many years ago and because it is almost invisible forgot about it.
The Thermal switch opens if it sees temps below freezing. This should only happen under two conditions.
1. Outside temp is very low. Many older Corvettes are not driven in the winter.
2. it the freon level in the system is low the evaporator can freeze up, but you don't want your AC low on freon. If it gets too low the compressor might seize.
If you are not able to come up with a switch, temporarily jumping the leads together will allow the compressor to run.
DocRebuild has some amazing color charts showing the various connectors used throughout the Corvette. They can be life-savers if you are not familiar with the connectors used on your particular year Corvette.
I strongly suggest that you take a look at his website a look at the OSOEZ wiring guides. Doc Rebuild is a great supplier of quality parts and I use him often.
I've been purchasing quite a few items from Dr. Rebuild. Great quality parts. Took a while to get the ordered items....and the website is archaic and tough to navigate...but there's a charm in all of that!
Thanks!
Originally Posted by ctmccloskey
DocRebuild has some amazing color charts showing the various connectors used throughout the Corvette. They can be life-savers if you are not familiar with the connectors used on your particular year Corvette.
I strongly suggest that you take a look at his website a look at the OSOEZ wiring guides. Doc Rebuild is a great supplier of quality parts and I use him often.
Update: I believe that the orange wire in question is a factory installed bit of wiring.
As Robertea points out, A/C was an option with it's own separate harness but the need to bring to bring power to the blower relay necessitated the orange wire from the horn relay. The orange wire, as you can see from the photo is 'woven' through the the A/C harness which I doubt a previous owner would have done. Thus, the wire was external to the engine harness and not woven into the wire stack with tape. My orange wire was secured to the harness with wire ties that see too comtemporary for 1971, though.
I have the engine wiring harness out of the car for assessment on whether to re-wrap it or opt for a replacement harness.
Do you have the '71 assembly manual? With a car in pieces, I'd think it would be the #1 reference for me!
Here is the illustration for the A/C firewall stuff - your side hole in the box is #9, a switch, view B. I can take a few pics of my '72's orange wire routing. Do you have the wide strap style "zip" ties along the firewall?
Hello,
About a new engine harness.....
When I was restoring my 71 I had all the harnesses out at the same time.
I was able to get a good look at them.
They had never had any work on them.
I noticed pretty quickly that they were in very good condition except for the engine harness.
My thought was that the engine harness had lived it's life in a difficult environment...heat, gas, oil, and dirt.
It's probably the easiest of the harnesses to replace.
Maybe?
Regards.....
Hello,
About a new engine harness.....
When I was restoring my 71 I had all the harnesses out at the same time.
They had never had any work on them.
I noticed pretty quickly that they were in very good condition except for the engine harness.
My thought was that the engine harness had lived it's life in a difficult environment...heat, gas, oil, and dirt.
It's probably the easiest of the harnesses to replace.
Maybe?
Regards.....
I agree it's easy to replace. For my '72 the deciding factor to go with a new harness was that the connectors were beat up, melted, or gone. A few of the wires were pretty stiff and baked. Lectric Limited's diagram was also good to see what's what.
I do have the '71 AIM, but darned if I can find that page. Coming to terms with the AIM and finding the right pages has proven elusive. Is that in the optional equipment section?
My wire had thin zip-ties securing it which, to my eye, did no look correct. Which ties shoud be used?
Thanks!
Originally Posted by barkingrats
Do you have the '71 assembly manual? With a car in pieces, I'd think it would be the #1 reference for me!
Here is the illustration for the A/C firewall stuff - your side hole in the box is #9, a switch, view B. I can take a few pics of my '72's orange wire routing. Do you have the wide strap style "zip" ties along the firewall?
I agree on replacing the harness...actually all the harnesses, but the project is becoming a bottomless pit. I'm going to try to rewrap the harness, clean up the wires and replace connectors where needed and see how that turns out.
I really appreciate offered comments here. They are deeply valued and considered.
Sorry I've been slow to respond. Drove up to New Jersey (now known as Ice Station Zebra...it was 7 degrees this morning there...). Picked up a hard top, an accompanying stand and a set of NOS rally wheel trim rings. I'm back in 'warmer' climes as its a bearable 28 degrees here in Virginia.
I do have the '71 AIM, but darned if I can find that page. Coming to terms with the AIM and finding the right pages has proven elusive. Is that in the optional equipment section?
My wire had thin zip-ties securing it which, to my eye, did no look correct. Which ties shoud be used?
Thanks!
Yes, that page is in the C-60 option pages —in the '72 AIM, it's on page M338.
The main standard build of the car is in the first half of the AIM then the option pages follow and are arranged in alphabetical order by option code and number. The option codes are pretty easy to remember for the popular ones: A=windows, C=A/C, J=brakes, L=engines, M=transmissions, N=steering, P=tires, U=radios.
The proper harness and hose ties should be about 1/4" wide and I believe are shown in the AIM where applicable. You have one in this pic on the far right edge. They should all look like this one.
Hi Alan:
Turns out that once I removed the harness sheathing (which was dry and brittle...) the wires were in remarkable condition given the years. I suspect that I'll run into the same circumstance with the lighting and A/C harnesses, too. I've bought some 3/4" harness tape from Zip and I'm in the process of rewrapping (after cleaning, of course). I'll post a picture when I'm done...
Cheers,
Bob
Originally Posted by Alan 71
Hello,
About a new engine harness.....
When I was restoring my 71 I had all the harnesses out at the same time.
I was able to get a good look at them.
They had never had any work on them.
I noticed pretty quickly that they were in very good condition except for the engine harness.
My thought was that the engine harness had lived it's life in a difficult environment...heat, gas, oil, and dirt.
It's probably the easiest of the harnesses to replace.
Maybe?
Regards.....
Rewrapping the wire harnesses is a real PITA. I have done several of mine over the years using the non-sticky harness tape. I was on a website, perhaps in was Lectric Limited, and there was a video of them making a harness and the machine that wraps the harness. I was amazing to watch it take almost no time to wrap the complete harness. Made me wish there was an easier way to do it when the harness was still in the car. I undid the functional TI harness because I couldn't figure how there were a different number of wires going in than coming out and they were different colors. Drew a picture of the TI circuitry along with the harness so that I could remember in the future.
With the harness out of the car, it was a lot easier to wrap it. I used the 3/4" non-sticky harness tape and it all went smoothly. The leads going to the starter had a heat resistant encasement which was oil soaked and practically fell-off the lead. I had some similar heat resistant fabric material with which I wrapped the leads and then finished the full harness with the non-sticky tape. I also spent a lot of time cleaning the goop from the junction block. They liberally squirted a seam-sealer like material on it. In the end, it came out great.
Now, onto the lighting harness. I'm struggling with the fiber optic cables. They seem securely lodged in the center console loom; I'd hoped that they would come loose and I could pull the cables through the firewall. Failing that, I'll need to open the harness sheathing and realease the cables so I can pull them into the interior. Unless there's a better way?
Bob Full engine harness junction block starter leads fiber optic loom
Originally Posted by robertea
Rewrapping the wire harnesses is a real PITA. I have done several of mine over the years using the non-sticky harness tape. I was on a website, perhaps in was Lectric Limited, and there was a video of them making a harness and the machine that wraps the harness. I was amazing to watch it take almost no time to wrap the complete harness. Made me wish there was an easier way to do it when the harness was still in the car. I undid the functional TI harness because I couldn't figure how there were a different number of wires going in than coming out and they were different colors. Drew a picture of the TI circuitry along with the harness so that I could remember in the future.
Engine Bay Harness Wire?
