I have a 2004 Ford F150 5.4l V8. A year ago it stopped working. Stays bellow the 'C' line, doesn't move. A/C still blows cold air. It randomly worked acouple days ago, then stopped again. I'm way over due on troubleshooting this. Sounds like it can cause serious issues if not fixed, which I didn't realize. Any ideas?

 

Any takes?
Just to add. Truck drives fine, a/c works fine
everything seems okay, just the temp gauge wont move, always under 'C'. Every once in a blue moon, it'll randomly work and read random readings and sometimes correct reading, but very very rare it reads at all.

 

Well based on which engine you have I do believe that it may not have a coolant temp sensor it may use info from the cht to infer coolant temp.

What I would suggest is to get a OBD2 device which can monitor the pid for the engine temperature and see if it seems correct. If it seems right then the issue is likely in the instrument cluster itself. It seems there are various functions that can fail due to bad solder joints and perhaps this is one of them?

 

Really appreciate the help. I do have a ODB2 reader. Have a feeling it might be a bad cluster/wiring because my truck is acting normal. We'll see.. Will check the readings and will update back with results!

 

My ODB2 reader is broken. Screen is all messed up after doing software update. Tried fixing the issue but can't, spend hours. It's a goner. Need to buy a new one. One code that I did pull up and read right before it broke, is code P0175.

Edit: I just read online...
"I strongly suggest verifying that the cooling system of the vehicle is working correctly. If the vehicle is running abnormally cool, the engine will always run in a rich condition. This is because the ECM is designed to run at a rich rate when cold to help warm the engine up faster. If the coolant temperature sensor is faulty or the thermostat is stuck open, the vehicle may never reach a warm temperature, which will cause it to always run in a rich condition."

So this would lead me to believe that it is indeed a faulty CHT?

 

Id not assume that from the given info.
buy or borrow a scanner and see what it says for cht. Or maybe those ones at AutoZone they scan for you could tell you?
If the PCM detects too low of temps it throws a code, so I have my doubts that is your issue

 

Got me a OBD2. Live readings have my Coolant temperature reading a consistent 192F. Air intake is reading consistent 111 when driving around neighborhood. MAF(lb/s) reads 0.01 idle and 1.0 give or take when pushing down acceleration. Not sure what else to read.

Still coolant temp gauge is stuck at bellow 'C'.

Well darn. I guess this means a possible bad instrument cluster. I just noticed now that whenever I turn the key and my cluster turns on. All the needles move to their appropriate position but the coolant temp needle sort of vibrates/flickers in the same spot under the 'C', then just stays there completely still after flickering for a half second. Just noticed that.

I'd like to do a instrument cluster reset/test but can't find anywhere how to do it. It's for a Lariat. I see vid tutorials on similar ford trucks of that year but they have that little pin button coming out the glass, which I don't have.

 

wonder if this 2004 is a Heritage ?

 

It's the new style 04-08, lariat

 

Since it sometimes works, it sounds like a wiring connection issue. To troubleshoot I'd start at the instrument cluster by removing the covers over the wire connectors. Then, with the engine running I'd watch the temp gauge while jiggling the wires. Would also disconnect the wire connectors to see if all pins are making good contact and spray both with wire connection cleaner. Would also tap around on cluster as needed to see if that causes needle to move. If none of this worked, I'd remove, disassemble, and remelt each solder joint. If the problem persists, I'd check for power to the temp gauge wires.

Good luck.