I have just completed changing out the dreaded Heater core unit on my Blazer. All was successful and all went well.

However the temperature guage is stuck on 100. I plugged all the plugs back in when putting the dash back together. I thought it could be an air lock in the system so the sender was not sitting in water. Since first topping up I have run it and let it cool enough to open it up and get some more coolant in, I am not pretty sure it is sitting coolant now.

I measured the resistance of the sender unit and it read open circuit, this is not the correct reading and would suggest that it has gone bad. It was working fine 2 days ago before I began the heater core job. The wires connecting to the sender unit measure a good 5 volts accross them, so the computer seems to be supplying the correct power to the sender unit.

I guess I am now going to change out the sender just for the hell of it anyway to see what happens, although I find it mighty strange that it has suddenly gone bad just as I was working on the system.

My question is: Is there anything I could have done to cause this when I had the dash apart fixing the Heater core?


Blazer 4.3 1996 V6 4 X 4

Now I am really confused, can someone help?

I am reading in this forum that there is a temperature sender and a temperature sensor??

The unit I was working on was right by the thermostat housing.

 

You have two. I can't remember off the top of my head which is which. I seem to remember the one on the water neck being the PCM sensor and the one on the driver side cylinder head being the gauge sending unit.

 

I am guessing I need to track down the SENDER unit.

Can anyone give me the exact location of this? Whereabouts on the drivers side cylinder head?

 

You should find the 1 wire temp sender for the temp gauge on the driver's side between & just above the back 2 spark plugs.