Engine Temperature Gauge not working

[MalibuHacon]

My temp gauge is stuck in the lowest possible reading all the time, i have the sport dash with the temp, volt, and oil gauge in a 1980 Malibu. I looked through some videos on youtube and everybody suggested that a ground wire on the engine-block was usually the cause when gauge is stuck at lowest reading, but to my surprise there was no trace of it... I also noticed that on top of the engine one of the things that looks like sensors didn't have any vacuum lines...

Can anybody shine some light on this issue, is the ground wire possibly placed somewhere else on the Malibu vs caprice/truck? or is the disconnected sensor-thing the culprit?

Its the blue thing to the right above the radiator hose that is seemingly not connected to anything, is this the sensor possibly?

 

[pontiacgp]

this looks to be the problem if I am seeing what I think I am seeing. The temp sender wire is not attached to the sender. It's a green wire.

 

[MalibuHacon]

Alright, you are talking about the little round thing that sticks out between the 1 and 2. spark plugs?

Where does the green wire exit the firewall? haven't seen a trace of it..

 

[Ribbedroof]

The green wire exits the firewall through the engine harness side of the bulkhead connector, and is sometimes tucked in the headlamp harness conduit.

 

[MalibuHacon]

Okay, thank you. I have replaced my fender, that probably explains why my green wire is missing.... now I just have to find it

 

[MalibuHacon]

Alright, figured it out, if found the green wire, however the connector was square and would not fit on the sensor. The sensor has a round connector that would never fit on the wire connector, is the sensor missing a piece?

However I tested the wire at a ground surface and got a full reading in the gauge (gauge is working). And wrapped a new wire around sensor and it now works. but the temp did not go over right between 100 and 220, isn't that suspiciously low?

^For testing purposes only, ended up cleaning it up and wrapping it more tightly

 

[ldr]

If the needle is at operating temp, I would say it's around 190°. That's where mine run with that type of gauge and ecu temp was 190 to 195.

 

[Ribbedroof]

The connector should have a slot on the plastic shell. It slides on sideways over the nipple on the sender. It will be parallel to the cylinder head when installed, not perpendicular.

Should look similar to this (shell is probably white rather than black)

 

[Ribbedroof]

The gauge scale is not linear, reading shown looks about normal if at operating temp.

 

[MalibuHacon]

Ribbedroof, ok so on the side of the nipple?

I'll look into it. Glad I i didn't cut the connector on the wire as I did consider it.
maybe it was just way to greasy for me to see anything