Hi all, I've got an issue with my 2004 F150 Lariat. I replaced the original engine with a new one from Powertrain. I've put a few hundred miles on it, and it runs great. The first cold morning that I drove it, I noticed the temperature gauge not registering where it normally does. After about 50 miles CEL came on, don't remember the code number, but it was coolant temperature too low. When I replaced the engine, I replaced all the parts of the cooling system. My first thought was maybe the thermostat was sticking open so I checked it first and it's working fine, coolant level was good also. Must be the CTS sensor under the intake of course since it was the one sensor that I didn't replace. That didn't fix it either. Then I unplugged the sensor and checked the voltage at the plug with the KOEO, I believe I read through searching it should register 5 volts, it read exactly 5 volts. I checked the ground at the plug and it checked good as well. I read that the PCM sends the signal to the temp gauge. I also tried the "gauge cluster check" but I haven't got it to work for me ? If anyone has any ideas, or can help me troubleshoot this issue, I would be grateful. Thank you.


v/r,
Parker

 

1.With the key in the ignition and in the off position press and hold the odometer / trip button.

2.Turn the truck to ‘On’ but do not start the truck.

3.After a few seconds the gauges will sweep from nothing to max, release the odometer / trip button.

4.The odometer should now read ‘GAUGE’, you are now in a information mode.

5.Start the truck

6.Now every time you press the odometer / trip button it will cycle through the information available.

7.When you shut the truck off the odometer will go back to showing mileage.

 

Did you change the thermostat? With a lower temp setting?
On my 2000 F150 I had the larger radiator from a 7700 truck installed. A winter or two after that in while working in Wisconsin, I started getting a trouble code about the engine not warming up quick enough. The dealer diagnosed it as needing a new thermostat which was probably correct. But, I just cut a piece of corrugated cardboard about 20" square and dropped it between the radiator and the condenser and that cured the problem of warming up too slow. When the weather warmed I took the cardboard out and it was in perfect shape looking like it never got wet during its time between the radiator and the condenser.

 

Roadie makes a point - you need at least a 190 thermostat and OEM recommended, not aftermarket.

To see if it's a gauge issue or not, a decent scanner/code reader can read out the temperature being reported. Then you can use a IR thermometer gun to see what the temperature is at the thermostat housing to see if it's really running cold or it's not being reported properly.

 

ManualF150, thanks for your reply. I did exactly as you laid out, but the gauges never sweep ?

 

Roadie, thanks for your reply. I installed a new ​​​​​​​Motorcraft 7L3Z8575D thermostat (192 degree) when the new engine was swapped.

 

Any other ideas ? Thermostat was new Motorcraft 192 degree

 

Wanted to post an update. I fished the wire harness back under the intake. I removed the alternator so I could squeeze my hand into the tight spot and plug in the sensor. Topped off the coolant and fired her up. I hooked up my scanner and waited for it to warm up. So far it's working as it should, temperature according the scanner was 194 degrees and the gauge registered to the half mark like it normally does. I honestly think I didn't let engine warm up enough after swapping the CHT sensor. I'll keep an eye on it.