paulebrown

...What does it do? The "Transmission Control Spark switch has been disconnected as long as I can remember. I finally figured out what that green wire goes to. Anybody?
pb

Mike Ward

Generically, it locks out vacuum spark advance under certain conditions. When and how changes dramatically depending on what year, engine and transmission you have. The archives are full of discussion on this.

paulebrown

Thanks Mike,
I'll check archives.
pb

PS
Just checked it. PFM????
I guess I ain't gonna worry about it.

7T1vette

TCS is an emissions item only. With it active, the timing is retarded at idle (vacuum is blocked so that vacuum advance can on the dist is not operational until throttle is depressed). It only serves to run your engine hotter at low speeds (which burns more hydrocarbons...but does no good for your engine). If you want the car to "look" factory correct, leave the equipment on the car but fix it so that it is non-functional. Otherwise, put that stuff in a bag and store it somewhere.

Duke94

Here's a link, go to page 4.

Gary

http://ncrsrmc.org/Downloads/Mar-2006-Newsletter.pdf

kdf1986

My TCS unit was installed on my 73, but not connected to anything. I found out what it was for, and did not bother to hook it up. I did remove it and keep it in a bag for future use. I checked online and they are pretty expensive units to replace. Around $85 - $100 with online vendors.

kdf

Peterbuilt

On my 74 350 auto the "Emissions Sticker" says CCS-EGR
The 74 Service Manual has no information on CCS but there is information on "Transmission Controlled Spark System" so my question is are these both the same with the exception of the vacuum advance solenoid being a separate unit and attached to the coil rather than the combination unit of idle stop solenoid and vacuum advance as shown on the NCRS 71 info?

flaco1801

not sure the 74 automatic had a tcs, might have been just the manual tranny...

CraigH

Here is an earlier discussion around the 1971 CEC/TCS system.

Keep in mind 71 was unique but many of the basics are similar.

http://forums.corvetteforum.com/c3-t...id-wiring.html

paulebrown

Thanks, Gary, for the link: I am always amazed at the resources of this forum.
I bought this car new in 72 and one of the first things I did was have someone remove the "polution control" stuff. And that was part of it. After 39 years the memory dims somewhat about all the things one does to one automobile.
pb

Mike Ward

PFM? Pure F'ing Magic.