Is this normal? I have owned this 2018 truck since Jan. I'm pretty good at checking my guages, not just while driving, but just after start up. I just noticed that the trans temp guage takes a minute or two to register. Is this normal, and how could I have missed this before if it's not new.

 

Normal. You obviously weren't checking as closely as you thought you were.

 

Yep, normal. Both my F150s have done that.

 

I must be getting old and losing my touch.

Gives me a little peace of mind if you guys say it's normal. Just dropped the truck off for the CEL related to the phasers, and told the shop owner to take it home after to be sure they got it right this time. Might have to have a fluid and filter change in tranny, it just started to not want to shift into 10th unless I put it in manual mode.

 

I asked the same question earlier this year. Takes a minute register after a hot restart.

 

Well now, being an engineer, I have questions on why it works this way. I am sure it has to do with the electronics, my education is in mechanical. Is it some sort of thermocouple that runs on low voltage?

 

The TFT (Transmission Fluid Temperature) gauge is a thermistor device. A reference voltage is passed through the sensor and the resulting output voltage is monitored by the PCM.

The gauge is not directly connected to the temperature sensor. The temperature sensor in the transmission sends a signal to the PCM via a hardwire. The PCM interprets the signal and makes the transmission fluid temperature avaiable on the CAN. The PCM sends the transmission fluid temperature over the HS1-CAN bus to the IPC. The IPC determines were the gauge pointer should be based on the received TFT, then moves the pointer on the gauge. The TFT is only sent to the IPC on a scheduled interval rather than constantly. Hence, there is a delay in the gauge until the PCM sends the TFT to the IPC the first time and the gauge pointer moves.

 

Thanks for that detailed info. Being it's my first Ford, I'm still learning about this truck.

 

I actually missed a step. The PCM sends the TFT to the GWM over the HS1-CAN. The GWM in turn sends the TFT to the IPC over the HS3-CAN.

It is the way most vehicles work these days. CAN buses and communications.

I, BTW, am a retired mechanical engineer, but worked with a lot of electronics to make the mechanicals (engines, hydraulics, etc) work.

 

You can also see the temp in degrees in the dash display >screen< if stepped to see that reading.
It may also be seen in Dash Engineering Mode but in Degrees C.
Temp comes up slowly because it's not a direct part of the engine cooling system. like old designs.
If you look under the truck, right at the front of the Trans, you will see the Cooler. There are no cooler lines going to the radiator.
Cooler has its own Thermostat to control internal fluid flow. This is what's on a 5 L engine equipage.
Good luck.