Thermal Transmitter Question...did search

[kcdc]

Question for the guru's,

I searched the FSM, the EFI Troublshooting doc & this site. The closest answer I found was here: http://www.classiczcars.com/forums/showthread.php?t=12985&page=2&pp=15&highlight=thermal+transmitter

Is the Thermal Transmitter basically a sending unit for the guages? If so, which guage? I "assume" the Water Temp Switch sends the temp guage signal. I'm learning the workings of the efi cold start system (for lack of better description), but these two are my missing links...

Bambikiller, Sblakley01???

Thanks in advance...

KCDC

Keith

[sblake01]

Thermal transmitter is just another name for the water temp switch.

[kcdc]

Thermal transmitter is just another name for the water temp switch.

OK, but there is a Thermal Transmitter (with a single wire/ on upper left of housing) and a Water Temp Switch (with two wires/ a bullet & and a ground; on upper right of housing) right???

How do they differ?

Thanks...

KCDC

[sblake01]

Oh, my bad, it's been a while since I've dealt with those. The single wire one (thermal transmitter) is for the water temp guage and the 2 wire one (temp switch or temp sensor) is what the ECU uses to adjust fuel/air etc. based on the engines operating temp.

[kcdc]

Oh, my bad, it's been a while since I've dealt with those. The single wire one (thermal transmitter) is for the water temp guage and the 2 wire one (temp switch or temp sensor) is what the ECU uses to adjust fuel/air etc. based on the engines operating temp.

I thought that the Water Tem Sensor (bottom right of housing; with pain in the rear connector) was what the ecu used to adjust the fuel/air mixture

My Housing has (1976 280z):

- Thermal Transmitter - Upper left/ one bullet connector - FUNCTION - ???

- Water Tem Switch - Upper right/ two wire; on bullet & one ground loop connection - FUNCTION - ???

-Thermotime Switch - Bottom Left/ pain in the rear connector - FUNCTION - Tells the Cold Start Valve what the temp is and how long to stay on so it doesn't flood the engine

-Water Temp Sensor - bottom right/ pain in the rear connector - FUNCTION - Richens mixture until normal operating temp

Sorry to have so many questions, but I am really trying to understand this & learn the system.

It would be great if the Forum had perm/ sticky threads for tech discussion that explained systems like this

As always, you are appreciated...

KCDC

Keith

[sblake01]

That post made me go pop the hood on my 78. Evidentally, the 75-76 has what you're referring as 'water tem switch' where the 77-78 has a plugged hole. The rest of what you describe exists on my car. The thermal transmitter which I attempted to point out with the blue line, operates the water temp guage. The others do exist on both of my EFI cars and function basically as you described. What I was describing as the water temp switch or sensor is what you're referring as the water temp sensor. The 'water tem switch' (one bullet & one ground loop connection) doesn't exist on either of my cars. It must be specific to the 75-76 cars.

[kcdc]

That post made me go pop the hood on my 78. Evidentally, the 75-76 has what you're referring as 'water tem switch' where the 77-78 has a plugged hole. The rest of what you describe exists on my car. The thermal transmitter which I attempted to point out with the blue line, operates the water temp guage. The others do exist on both of my EFI cars and function basically as you described. What I was describing as the water temp switch or sensor is what you're referring as the water temp sensor. The 'water tem switch' (one bullet & one ground loop connection) doesn't exist on either of my cars. It must be specific to the 75-76 cars.

Didn't realize they were different depending on year model. Thanks for the expertise...

[sblake01]

Didn't realize they were different depending on year model. Thanks for the expertise...

Yes, they seem to be grouped 75-76 and 77-78. I'll check in my manuals once we get unpacked in the new house and see if I can find out anything about the water temperature switch. I can't find it on the microfiche CD.

[kcdc]

Yes, they seem to be grouped 75-76 and 77-78. I'll check in my manuals...

I could have missed it, but I did search my pdf FSM and came up with notta.

Anybody out there with a 75-76 know what the "Water Temp. Switch (upper right of Thermo Housing) is/ does & how it differs from the "Water Temp. Sensor" (bottom right of Thermo Housing/ pain in the rear type connector)???

[superwombat]

I'm dealing with the same thing on my 76 Z

If you have four guages there by the thermostat then you probably have a california model like I do.

The top left one with the single wire is for the temp guage in the dash, If you short it to ground with the key on the guage will go all the way to the top.

The top right one is for the Exaust Recirculation (California crap) it triggers the exaust recirc. once the engine reaches operating temp.

I haven't gotten to the bottom two yet, so I'm not sure on those.