Electrical question
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Electrical question
Hello
I am rewiring a 71 Corvette and could use some help identifying a wire and two metal cans.
There is a brown wire with a white stripe about 18ga. that comes out of the engine wiring harness at the fire wall and is long enough to run to the front of the motor then loops back and goes into the same harness. I believe this is an original production wire because it comes out of the original harness. I cannot find this wire on any wiring diagrams for a 71 that I have.
Also located on the engine fire wall left side is what appears to me what could be a circuit breaker. A small metal can that has two terminals with one connector. Mounted to this metal can is another metal can that has three electrical terminals on the bottom. I don't remember if there is one or two connectors that connect to this. But I know there are three wires that connect. On the top of this can I believe it says little fuse Incorporated. Again I cannot find this on my wiring diagram.
Any help would appreciated.
Charlie
I am rewiring a 71 Corvette and could use some help identifying a wire and two metal cans.
There is a brown wire with a white stripe about 18ga. that comes out of the engine wiring harness at the fire wall and is long enough to run to the front of the motor then loops back and goes into the same harness. I believe this is an original production wire because it comes out of the original harness. I cannot find this wire on any wiring diagrams for a 71 that I have.
Also located on the engine fire wall left side is what appears to me what could be a circuit breaker. A small metal can that has two terminals with one connector. Mounted to this metal can is another metal can that has three electrical terminals on the bottom. I don't remember if there is one or two connectors that connect to this. But I know there are three wires that connect. On the top of this can I believe it says little fuse Incorporated. Again I cannot find this on my wiring diagram.
Any help would appreciated.
Charlie
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Do you have power windows? The circuit breaker could be for PW. The A31 options section of the AIM should show it.
Pics would help.
Pics would help.
Last edited by Easy Mike; Dec 30, 2015 at 07:34 AM.
Le Mans Master
Joined: May 2003
Posts: 8,878
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
The brown white wire you are trying to identify-
It goes to a timer delay for the CEC solenoid-
Here's a thread on it-
https://www.corvetteforum.com/forums...id-wiring.html
It goes to a timer delay for the CEC solenoid-
Here's a thread on it-
https://www.corvetteforum.com/forums...id-wiring.html
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Good morning
Sorry about not posting a picture. I know how important they are when trying to solve a mystery. The car belongs to a friend of mine and I am helping him. I haven't taken any pictures. If we can't figure it out today I will try to get a picture posted.
This car does not have power windows. That's the first thing I thought about. You are correct the A31 options section of the AIM does show a circuit breaker in the correct position on the fire wall. But this car does not have electric windows and the 'believed' circuit breaker is wired.
I believe it is a circuit breaker. It is the right size and shape for a circuit breaker. The other can that is mounted in front of it is more of a square shape and it's just a little bit bigger of what I believe is a circuit breaker. It's like they are stacked in front of each other.
I would have included the wire colors and sizes but I was away from the car and couldn't remember when I posted late last night. I was hoping the answers to my questions would be easy but such is not the case many times when it comes to our favorite toys.
Will post today's results later this evening.
Thank you Easy Mike for your input.
Sorry about not posting a picture. I know how important they are when trying to solve a mystery. The car belongs to a friend of mine and I am helping him. I haven't taken any pictures. If we can't figure it out today I will try to get a picture posted.
This car does not have power windows. That's the first thing I thought about. You are correct the A31 options section of the AIM does show a circuit breaker in the correct position on the fire wall. But this car does not have electric windows and the 'believed' circuit breaker is wired.
I believe it is a circuit breaker. It is the right size and shape for a circuit breaker. The other can that is mounted in front of it is more of a square shape and it's just a little bit bigger of what I believe is a circuit breaker. It's like they are stacked in front of each other.
I would have included the wire colors and sizes but I was away from the car and couldn't remember when I posted late last night. I was hoping the answers to my questions would be easy but such is not the case many times when it comes to our favorite toys.
Will post today's results later this evening.
Thank you Easy Mike for your input.
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi cgc,
The 2 small relays are part of the 71 Combined Emission Control system.
They're the 'reversing relay' and 'delay timer relay'.
The long lead sounds like the lead fot the CEC solenoid that's mounted on the left front of the carburetor. What does the connector look like? That you say it 'loops' back to the harness puzzles me.
Regards,
Alan
The exact configuration of the relays varied through the production year.
You can see the wrapped black tape wrapped lead in the 2 clips on the side of the valve cover. Please disregard the configuration of the distributor shield in this picture.
The 2 small relays are part of the 71 Combined Emission Control system.
They're the 'reversing relay' and 'delay timer relay'.
The long lead sounds like the lead fot the CEC solenoid that's mounted on the left front of the carburetor. What does the connector look like? That you say it 'loops' back to the harness puzzles me.
Regards,
Alan
The exact configuration of the relays varied through the production year.
You can see the wrapped black tape wrapped lead in the 2 clips on the side of the valve cover. Please disregard the configuration of the distributor shield in this picture.
Last edited by Alan 71; Dec 30, 2015 at 09:46 AM.
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
The brown white wire you are trying to identify-
It goes to a timer delay for the CEC solenoid-
Here's a thread on it-
https://www.corvetteforum.com/forums...id-wiring.html
It goes to a timer delay for the CEC solenoid-
Here's a thread on it-
https://www.corvetteforum.com/forums...id-wiring.html
I followed the link you provided and a post by CraigH included a Photo of the CEC solenoid time delay relay. The can that is mounted in front of the circuit breaker on the fire wall of the car that I am working on looks exactly like the relay in the photo.
I think some of the mystery wiring that I am dealing with is what remains of the old CEC system.
Many thanks
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Hi cgc,
The 2 small relays are part of the 71 Combined Emission Control system.
They're the 'reversing relay' and 'delay timer relay'.
The long lead sounds like the lead fot the CEC solenoid that's mounted on the left front of the carburetor. What does the connector look like? That you say it 'loops' back to the harness puzzles me.
Regards,
Alan
You can see the wrapped black tape wrapped lead in the 2 clips on the side of the valve cover. Please disregard the configuration of the distributor shield in this picture.
The 2 small relays are part of the 71 Combined Emission Control system.
They're the 'reversing relay' and 'delay timer relay'.
The long lead sounds like the lead fot the CEC solenoid that's mounted on the left front of the carburetor. What does the connector look like? That you say it 'loops' back to the harness puzzles me.
Regards,
Alan
You can see the wrapped black tape wrapped lead in the 2 clips on the side of the valve cover. Please disregard the configuration of the distributor shield in this picture.
I post to slow!
No need for me to post a picture of the "cans" you did it for me.
That is exactly what I have.
The brown/white wire has never been cut and has no connector on it. It simply leaves the harness runs the length of the motor turns around runs the length of the motor and enters the wiring harness and disappears. It it like it was never used.
Thanks
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi cgc,
Just where in the harness does the br/w wire exit it?
Is it a 71 harness?
The connector for the solenoid is typically an opaque white plastic.
I still would be interested in seeing a picture of the relays if you can!
Regards,
Alan
Just where in the harness does the br/w wire exit it?
Is it a 71 harness?
The connector for the solenoid is typically an opaque white plastic.
I still would be interested in seeing a picture of the relays if you can!
Regards,
Alan
Last edited by Alan 71; Dec 30, 2015 at 10:48 AM.
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Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Alan 71 and any others
The first pic below show the looped end and the second pic shows the harness where the wires exit and enter.
Yes the harness is an original 71.
The relays are mounted next to the windshield wiper motor.
Let me know what you think.
The first pic below show the looped end and the second pic shows the harness where the wires exit and enter.
Yes the harness is an original 71.
The relays are mounted next to the windshield wiper motor.
Let me know what you think.
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi cgc,
Yes, those are the reversing relay and the delay timer.
The long wire…. I don't know…. is you harness an original harness that's been unwrapped or had some of the wires 'pulled' out of it.
So ???
Regards,
Alan
Yes, those are the reversing relay and the delay timer.
The long wire…. I don't know…. is you harness an original harness that's been unwrapped or had some of the wires 'pulled' out of it.
So ???
Regards,
Alan
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Alan
I wish I could answer if the wires were pulled out or if the harness has been untaped. I have no reason to believe the harness has been replaced. It was about 1985 when the deceased owner who I knew got this car. Him and his wife enjoyed this car a lot. It brought them a lot of pleasure. They both passed away about a year ago. Bob the owner had started a restoration but was unable to continue because of ill health. After their passing there daughter took position of the car. Her father in law a friend off mine ask met to help get the car back together. It has been a real challenge. Bob had pretty much gutted the car. We are still looking for missing parts. Since the motor and transmission were missing we thought this would be a good time to upgrade to a later set up.
All I can tell you about the wires is they come out of a harness that appears to be original and unmolested. It may be that these two wires may have been folded up because of the kinks in the wire. What you see in the photos is pretty much what I saw the first time.
Thank you Alan for taking such a interest and sharing your photos. You are such a credit to the entire Corvette World.
I wish I could answer if the wires were pulled out or if the harness has been untaped. I have no reason to believe the harness has been replaced. It was about 1985 when the deceased owner who I knew got this car. Him and his wife enjoyed this car a lot. It brought them a lot of pleasure. They both passed away about a year ago. Bob the owner had started a restoration but was unable to continue because of ill health. After their passing there daughter took position of the car. Her father in law a friend off mine ask met to help get the car back together. It has been a real challenge. Bob had pretty much gutted the car. We are still looking for missing parts. Since the motor and transmission were missing we thought this would be a good time to upgrade to a later set up.
All I can tell you about the wires is they come out of a harness that appears to be original and unmolested. It may be that these two wires may have been folded up because of the kinks in the wire. What you see in the photos is pretty much what I saw the first time.
Thank you Alan for taking such a interest and sharing your photos. You are such a credit to the entire Corvette World.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The Chevrolet Chassis Service Manual for 1971 has a section that specifically details the Corvette CEC emission system. The is the best source of info related to this feature.
As I understand it, that "reversing" relay was a 'last-minute' hardware correction, as something else in that system was designed improperly (could be that other relay). It was too late to correct the problem, so another 'simple' relay was added to obtain the proper results.
The entire CEC system was a "Band-Aid" approach to get the base engines to pass emissions testing without having to install the A.I.R. pump (except in CA). There is NOTHING in that system that provides benefit to the vehicle, its operation, nor its performance. And, the amount of benefit it provided for emissions is questionable...but bureaucracy prevailed (EPA).
Unless you are just determined to rebuild the car exactly as it came from the factory, I would suggest that you either eliminate the CEC system or, at least, leave it intact but bypass it so that manifold vacuum is always sent to the distributor advance can. Your engine will run cooler at idle, will idle better, and your fuel mileage will go up a bit.
As I understand it, that "reversing" relay was a 'last-minute' hardware correction, as something else in that system was designed improperly (could be that other relay). It was too late to correct the problem, so another 'simple' relay was added to obtain the proper results.
The entire CEC system was a "Band-Aid" approach to get the base engines to pass emissions testing without having to install the A.I.R. pump (except in CA). There is NOTHING in that system that provides benefit to the vehicle, its operation, nor its performance. And, the amount of benefit it provided for emissions is questionable...but bureaucracy prevailed (EPA).
Unless you are just determined to rebuild the car exactly as it came from the factory, I would suggest that you either eliminate the CEC system or, at least, leave it intact but bypass it so that manifold vacuum is always sent to the distributor advance can. Your engine will run cooler at idle, will idle better, and your fuel mileage will go up a bit.
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi,
The CEC system is an instance when the Chassis Service Manual isn't the "best source" of information.
An additional Emissions Control publication was printed by Chevrolet and sent to the dealerships for use in the service departments.
Regards,
Alan
The CEC system is an instance when the Chassis Service Manual isn't the "best source" of information.
An additional Emissions Control publication was printed by Chevrolet and sent to the dealerships for use in the service departments.
Regards,
Alan
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Thank you 7T1vette for your reply.
Since the original motor went missing ( sorry but I hate that term) a long time ago and replacement motor also has gone missing we are taking this opt to install a later model motor and transmission. This car will be a driver for a little 'young' lady school teacher.
I personally can enjoy both a modified Corvette or a totally correct Corvette. I think there is room for both.
I own a 68 T top that I have restored as close to stock as I could with one big exception I installed an OD transmission. I have the original transmission.
Since the CEC system isn't needed we are removing it from the car. We are trying to identify and remove unnecessary wiring and clean up the wiring in this car from bumper-to-bumper.
Since the original motor went missing ( sorry but I hate that term) a long time ago and replacement motor also has gone missing we are taking this opt to install a later model motor and transmission. This car will be a driver for a little 'young' lady school teacher.
I personally can enjoy both a modified Corvette or a totally correct Corvette. I think there is room for both.
I own a 68 T top that I have restored as close to stock as I could with one big exception I installed an OD transmission. I have the original transmission.
Since the CEC system isn't needed we are removing it from the car. We are trying to identify and remove unnecessary wiring and clean up the wiring in this car from bumper-to-bumper.
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Alan71
Since the CEC system will not be used we are removing what was left of it.
I have come to the point of curiosity. There are a few wires in the engine compartment that we cannot identify. After looking at your last reply I see that there was a cold override temperature switch and also a transmission switch. I don't know how much time you want to devote to my curiosity but could you tell me the location of both switches and the wire colors and sizes.
Thanks
Since the CEC system will not be used we are removing what was left of it.
I have come to the point of curiosity. There are a few wires in the engine compartment that we cannot identify. After looking at your last reply I see that there was a cold override temperature switch and also a transmission switch. I don't know how much time you want to devote to my curiosity but could you tell me the location of both switches and the wire colors and sizes.
Thanks
Le Mans Master
Joined: May 2003
Posts: 8,878
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Hey Charlie-
Feel free to send me a email re wires not needed-
richard454 at comcast dot net
I've also done a more modern engine swap as well- went w/ fuel injection and four more cylinders.
I have mapped out all the wires from the firewall- as I moved my fusebox.
DSCN5033 by Richard Hayes, on Flickr
DSCN5172 by Richard Hayes, on Flickr
Feel free to send me a email re wires not needed-
richard454 at comcast dot net
I've also done a more modern engine swap as well- went w/ fuel injection and four more cylinders.
I have mapped out all the wires from the firewall- as I moved my fusebox.
DSCN5033 by Richard Hayes, on FlickrDSCN5172 by Richard Hayes, on Flickr
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi cgc,
There are 5 pieces of hardware in the CEC system.
1. The 'solenoid' on the carb. A 2 wire lead exits the harness to the rear of the distributor.
2. The 'reversing relay' on the firewall. A single ground wire, a single wire w/c connector, a 3 wire connector
3. The 'delay timer' on the firewall. 2- 2 wire connectors.
4. The temperature sensor (for this system, not for the dash gauge) in the passenger side head. A short lead with connector exits the harness behind the right side valve cover.
5. The transmission 3rd-4th gear sensor in the transmission. A single black wire with a button connector exit's the harness behind the distributor.
All the wires EXCEPT #4 exit at the same place behind the distributor.
Regards,
Alan
#1
#2&3
#4
#5
There are 5 pieces of hardware in the CEC system.
1. The 'solenoid' on the carb. A 2 wire lead exits the harness to the rear of the distributor.
2. The 'reversing relay' on the firewall. A single ground wire, a single wire w/c connector, a 3 wire connector
3. The 'delay timer' on the firewall. 2- 2 wire connectors.
4. The temperature sensor (for this system, not for the dash gauge) in the passenger side head. A short lead with connector exits the harness behind the right side valve cover.
5. The transmission 3rd-4th gear sensor in the transmission. A single black wire with a button connector exit's the harness behind the distributor.
All the wires EXCEPT #4 exit at the same place behind the distributor.
Regards,
Alan
#1
#2&3
#4
#5
Thread Starter
Racer
Joined: Sep 2007
Posts: 288
Likes: 1
Alan71
Great pictures!
The only wires I recognize are the ones on the relays. We do have an orange mystery wire that looks like the one going to the solenoid but no blue wire. The orange wire shows up in the second picture in my yesterday's 3:50pm reply. It is the wire laying on top of the motor.
Again Alan I keep saying it, thank you
Great pictures!
The only wires I recognize are the ones on the relays. We do have an orange mystery wire that looks like the one going to the solenoid but no blue wire. The orange wire shows up in the second picture in my yesterday's 3:50pm reply. It is the wire laying on top of the motor.
Again Alan I keep saying it, thank you
