What is This?

tonyk72 · 01-21-03, 05:52 PM

I found this while I was changing the plug wires...its on the right hand side...looks like something should be plugged into it?

Chas · 01-21-03, 06:05 PM

i have a wire that is coming from the area near the pass. firewall , that looks like it should plug into that thingy....now i gotta find that on mine....is it on the pass. side ? i guess it is sensor.

tonyk72 · 01-21-03, 07:20 PM

yep, pass side, between plugs 6 & 8

Chas · 01-21-03, 07:27 PM

look for the wire....i think its dark green and a brown...out of the fire wall area near the control for the sensitivity for the factory alarm ,if you have it....when i get off work(3am detroit) i will take a look and let you know the exact color and where it comes from....maybe we both get lucky...thanks for the post

01-21-03, 07:38 PM

I don't know much about older vettes, but my room mate happens to be an old chevy gearhead...and we do more engine work in our garage than I think the local chevy dealer! It looks like it could be either an electronic oil pressure sending unit, or oil temp sending unit. Hope this helps!

DDLS1 · 01-21-03, 08:18 PM

tonyk72,

From what you describe, on the passenger side head. This is where the water temp switch is located that powers up the aux cooling fan on my 81 when the temp reaches 200(provideded the a/c is in use). I don't know if it was used in 72 for a similar purpose or not. The water temp sending unit to the temperature gauge is located in a similar spot on the drivers side head.

tonyk72 · 01-21-03, 08:24 PM

After some research, I found that its a Transmission Controlled Spark System...used to control exhaust emissions. Looks like I'm not controlling anything...

MacD2469 · 01-21-03, 08:40 PM

Quote:

Originally posted by tonyk72
I found this while I was changing the plug wires...its on the right hand side...looks like something should be plugged into it?

Tonk72,
I did a little looking, ok, I spent days under my car putting in and removing my transmission and starter... Other problems...anyway what you are looking at is the temp switch for the auxiliary cooling fan. there should be a light blue and a black wire that go to it. The black wire on mine is grounded to the flywheel dust cover, which I am sure its not supposed to be... LOL

The engine circuit diagram shows that its supposed to be a chasis ground so it works for now.

Its an ongoing project fixing all the jury rig'n....

Mac

82' Crossfire

68Roadster · 01-21-03, 08:54 PM

I have one catalog that lists a 70-72 switch called TCS Coolant Temp Switch and it fits into the R/H cylinder head......

No idea what TCS is and why yours is unplugged???

Another one of those things that make ya go "Hmmmmmm"

Cee

Tom73 · 01-21-03, 09:15 PM

That is part of the TCS system (Transmission Controled Spark). Part of the emissions. Check here: http://www.corvetteforum.net/c3/vett...ission/tcs.htm for some details on the system. This is specs for '73.

tom...

JohnZ · 01-21-03, 09:48 PM

It's the temp sensor that feeds the TCS (Transmission-Controlled Spark) delay relay; prevents the TCS system from operating until the engine warms up. After it warms up, the TCS system blocks vacuum to the distributor unless you're in high gear.

tonyk72 · 01-22-03, 08:40 AM

So in laymans terms? I'm still a little lost...is it part of the emissions control system?

I guess this is what people feel like when I start talking about PIX firewalls and NAT...you techies know what I'm talking about...

JohnZ · 01-22-03, 10:51 AM

Yes, it is part of the emission control system, but most guys with TCS just bypass it anyway, by running the vacuum line from the carb directly to the distributor vacuum advance canister instead of having it pass through the thermo-vacuum switch on the intake manifold. The TCS delay relay I mentioned in my post above, triggered by the sensor in the photo with nothing connected to it, just makes TCS inoperative (by opening the circuit to the thermo-vacuum switch) until the engine warms up. For best operation, you want TCS inoperative ALL the time (bypassed). For judging, however (if that's in your plan), the TCS system function is verified as part of the Operations Check.

tonyk72 · 01-22-03, 11:11 AM

Cool, Thanks John...
does this TCS gizmo stuff have anything to do with A.I.R. ?

JohnZ · 01-22-03, 11:24 AM

Nope - A.I.R. is a completely independent system, with no electrical controls at all - just blows fresh air into the exhaust manifolds or dumps the pump output through the little "muffler" based on a vacuum signal from the carb to the diverter valve on the back of the pump.