Hello all. I'm a brand new user on this site. Hoping someone here can help me out.


I have a 2002 F-350 6.8L, 4x4, crew cab, 8' bed, SRW, trailer tow pkg. I purchased it new in the fall of 2001. The truck currently has 54,000 miles on it (only gets used when I need to tow/haul something). It's kept in the garage and is in near showroom condition.


Everything on the vehicle is 100% functional except the transmission temperature gage. Even when the truck sits for weeks, the needle will move to mid scale as soon as the key is switched on - haven't even started the engine yet! Put the scanner on it - no codes stored.


I'm attempting to trouble-shoot the TFT (transmission fluid temperature) sensor. Found some documentation online on the 4R100 transmission. It shows an electrical connector on the solenoid body with pins for the thermistor (so I can measure its resistance). However, I can't find a connector anywhere on my transmission that even remotely resembles the diagram I found online.


Question 1: Does anyone else have this problem? When you first get in your vehicle and turn the key, does your tranny temp gage read "cold" just like the engine temp gage?


Question2: Does my truck have the 4R100 transmission? How can I verify that?


Question3: Can someone provide documentation on what connector and which pins are for the thermistor?


Thanks in advance.

 

If it is an automatic it is a 4R100. There is no other possibility.

If the trans is at least 50F the gauge will be in the middle. That's the way it is programmed.

 

So the temp sensor is an input to the PCM and the dash gage is driven by an output from the PCM. Is this how it works? I suppose if I had the right scan tool, I could read the TFT directly.

 

The temp sensor sends a signal to the PCM. The PCM interprets this signal and calculates a temperature. This temperature is sent to the dash computer, which decides where to position the needle in the gauge.

You can read the signal from the PCM. Scan Gauge is one that will do that, there are many more.