71 CEC solenoid issue
Thread Starter
Instructor
Joined: Oct 2005
Posts: 204
Likes: 4
From: Sunny Florida
71 CEC solenoid issue
I am chasing a CEC solenoid, (Combined Emissions Control) issue on a base engine turbohydromatic with a/c.
I have gone through most all the diagnostics but am at a loss as to where the transmission switch is located.
Any help is appreciated.
Steve
I have gone through most all the diagnostics but am at a loss as to where the transmission switch is located.
Any help is appreciated.
Steve
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It is inside the transmission on an automatic; it is on the linkage on a manual tranny, I believe. It is a single wire which passes a 12 vdc signal when the trans is in higher gear range(s).
Why do you want to make it functional? Emissions testing?
For normal driving, that system is not beneficial for the engine, for fuel mileage, or for your 'peace of mind'. If you need it operational for emissions testing, OK. When you are just driving it around, you might want to consider 're-routing' a manifold vacuum signal to go directly to the distributor advance can.
Why do you want to make it functional? Emissions testing?
For normal driving, that system is not beneficial for the engine, for fuel mileage, or for your 'peace of mind'. If you need it operational for emissions testing, OK. When you are just driving it around, you might want to consider 're-routing' a manifold vacuum signal to go directly to the distributor advance can.
Melting Slicks
Joined: Apr 2010
Posts: 2,795
Likes: 1,196
From: Canberra Australia
2025 C3 of the Year Finalist - Modified
As said its on the transmission and just eaths the wire.
I did the diagram after wanting to know how it all worked. The NCRS article is good but did not explain enough. I took the delay relay apart to see what was in side as well and watch its operation.
In the end I was fairly happy with how it all worked, then disabled it.
Covered here
http://forums.corvetteforum.com/c3-t...id-wiring.html
And here
http://forums.corvetteforum.com/c3-g...journey-2.html
I did the diagram after wanting to know how it all worked. The NCRS article is good but did not explain enough. I took the delay relay apart to see what was in side as well and watch its operation.
In the end I was fairly happy with how it all worked, then disabled it.
Covered here
http://forums.corvetteforum.com/c3-t...id-wiring.html
And here
http://forums.corvetteforum.com/c3-g...journey-2.html
Last edited by CraigH; Sep 9, 2013 at 04:48 PM.
Team Owner
Joined: Sep 2006
Posts: 31,280
Likes: 4,372
From: Westminster Maryland
Hi,
On the 4-speed transmission there was a sensor threaded into the side cover of the transmission. I believe the connector is called a button type.
Not sure about the auto transmission sensor.
In 71 the CEC system increased the minimum idle speed in both 3rd and 4th gears.
Regards,
Alan
On the 4-speed transmission there was a sensor threaded into the side cover of the transmission. I believe the connector is called a button type.
Not sure about the auto transmission sensor.
In 71 the CEC system increased the minimum idle speed in both 3rd and 4th gears.
Regards,
Alan
Thread Starter
Instructor
Joined: Oct 2005
Posts: 204
Likes: 4
From: Sunny Florida
71 cec solenoid
7T1vette
Thanks for the reply. The black wire disappears into the wiring harness and and I do not see it feed back into the turbo hydramatic from below the car.
I am looking to have the car judged so that is the reason for the restoration of the system and checking the trans switch
I currently have the vacuum routed to the carb since without the cec functioning it runs badly
Craigh
Awsome diagram to go along with the article
and an amazing journey
Thank you very much
Alan,
I appreciate the input
The cec brings the idle up with the automatic trans with the a/c as well
I have chased the 71 combined emmission control system training manual with troubleshooting guide and am still at a loss.
12v to the solenoid at ignition on but no activation,
tried grounding test to delay relay, temperature switch, trans switch wiring, reversing relay.
Still no activation of the solenoid.
Solenoid works with grounding it with key on at the carb.
Replaced the delay relay and reversing relay and checked all the connections and fuses. I am thinking there is a ground issue somewhere or possibly the blocking relay may be an issue
reversing relay gets warm with key on.
Thank you all for the help, will keep looking
Thanks for the reply. The black wire disappears into the wiring harness and and I do not see it feed back into the turbo hydramatic from below the car.
I am looking to have the car judged so that is the reason for the restoration of the system and checking the trans switch
I currently have the vacuum routed to the carb since without the cec functioning it runs badly
Craigh
Awsome diagram to go along with the article
and an amazing journey
Thank you very much
Alan,
I appreciate the input
The cec brings the idle up with the automatic trans with the a/c as well
I have chased the 71 combined emmission control system training manual with troubleshooting guide and am still at a loss.
12v to the solenoid at ignition on but no activation,
tried grounding test to delay relay, temperature switch, trans switch wiring, reversing relay.
Still no activation of the solenoid.
Solenoid works with grounding it with key on at the carb.
Replaced the delay relay and reversing relay and checked all the connections and fuses. I am thinking there is a ground issue somewhere or possibly the blocking relay may be an issue
reversing relay gets warm with key on.
Thank you all for the help, will keep looking
