It grounds the signal from the temperature gauge so the temperature gauge works.
Tem sensor
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
One green wire is fine but if it is disconnected (you said it was) and the gauge is working then there is some home-made wiring to another sensor somewhere else. Usually on top of the intake manifold
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
Not on a '74 corvette it is not. That is the stock location for the coolant temp sensor for your temp gauge on your dash. There was not an electric fan, only thermostatic.
Last edited by LeMans Pete; Mar 7, 2013 at 04:46 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Sorry, but you are incorrect. You are thinking of a C2. If it was on the passenger side near the back cylinders that would be the TCS (transmission controlled spark) switch.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
Likes: 11
From: Hinckley OH
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
As Mike wrote, your AIM page shows it to be the coolant temp sensor and the only thing that sensor does is make the coolant temp gauge move. Look at the FWD mark on the page. That is clearly the driver side of the engine. So, you're either showing the wrong AIM page and it is the TCS on the passenger-side head that is in question, or you have a coolant sensor mounted elsewhere on the engine.
Pro
Joined: Nov 2012
Posts: 672
Likes: 0
From: Chesapeake Virginia
ok, lets look at it closely shall we----- the drawing calls it out as a "SW" which is customary for "switch", unlike the temperature "sensor". also-- if you look at note #1 in the comments section of the drawing it says that the switch was relocated. if it's a two wire connection, it is a simple on/off switch, if it only a one wire unit--it works on resistance to ground which is supplied by the engine JMHO
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
ok, lets look at it closely shall we----- the drawing calls it out as a "SW" which is customary for "switch", unlike the temperature "sensor". also-- if you look at note #1 in the comments section of the drawing it says that the switch was relocated. if it's a two wire connection, it is a simple on/off switch, if it only a one wire unit--it works on resistance to ground which is supplied by the engine JMHO
Note 1 may be specifically talking about relocating the alarm switch(?). Again, there were no electric fans on the corvette; therefore, no temperature switch.
Here is the temp sending unit that threads into the head at that location.
Last edited by LeMans Pete; Mar 8, 2013 at 03:11 PM.
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
I'm curious, did '74s have the TCS switch in the RIGHT cylinder head? Has the OP posted the wrong page of the AIM? That would be a two wire switch, and if this is disconnected, would obviously not affect his temperature gauge.
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
Guys, the drawing is correct, I'm pointing this item on the driver side. The wire that goes to this item has two wires, one of them is disconnected... Temp gauge is ok, also the engine is not the original one but a crate one...
Pro
Joined: Nov 2012
Posts: 672
Likes: 0
From: Chesapeake Virginia
Jig, unfortunately that is not the case. That is the stock location for all C3s, as far as I know. This location was not relocated.
Note 1 may be specifically talking about relocating the alarm switch(?). Again, there were no electric fans on the corvette; therefore, no temperature switch.
Here is the temp sending unit that threads into the head at that location.
Note 1 may be specifically talking about relocating the alarm switch(?). Again, there were no electric fans on the corvette; therefore, no temperature switch.
Here is the temp sending unit that threads into the head at that location.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
NOT all C-3's, My '81 has a factory electric fan and the switch for it is located in the drivers side head, the sensor for the coolant temperature is located on the intake manifold just adjacent to the thermostat goose neck, maybe the engine he has was pulled from a later model vette and they just left that switch in place
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
My guess is that the car does not have a 1974 front wiring harness.
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
Have you found another source for the temperature gauge, maybe on the manifold as some have suggested? Do you have electric fans? Any pictures of your engine bay?
Last edited by LeMans Pete; Mar 8, 2013 at 05:50 PM.