bushwicbill

Hello All...
I have a 2004 V8 5.4L Triton FX4 with 182,xxx miles. My temp gauge has been acting up for some time now. I will get in and it will already be showing a reading. I changed out the thermostat a few months back and no change. It has coolant and has enough in it. I'm not getting any warning indicators either. The truck is running fine, no hard starts, no knocking or lag when i step on the gas. Its starting to happen more often not now. Some days it will operate just fine. Those days are getting shorter and shorter. I was wondering if it could be my CHT sensor or the gauge cluster. Those are the only things i could think of. Any help or info would be greatly appreciated.



It was over 3/4 before i even put the key in. This was after 5 min of driving.

Z7What

Sounds to me like a faulty gauge or bad water temp sensor.

Wayne

bushwicbill

The water sensor that your talking about is that the same as the cylinder head temp sensor? Im not finding anything on a water sensor.

Z7What

After some research I learned that the 3V 5.4L uses a CHT sensor and not a ECT sensors. The sensor is cheap, I would start there!



Wayne

bushwicbill

Thank you! Now that i have a direction i just need to free up the time.

F150Torqued

@bushwicbill ;

WAIT. NOT SO FAST PICKING A DIRECTION AND FREEING UP SOME TIME.


What @Z7What suggests may be correct about the $COST$ of the part, but I beg you to do more diagnostics before you decide to replace the CHT. For sure, before you do, take a look at this link:


https://www.f150forum.com/f4/removin...nifold-285906/


The CHT is located UNDER THE INTAKE MANIFOLD, on the rear of bank 1 cylinder head between intake ports 2 & 3. I would recommend you get MORE diagnostic information before you tackle this much work.


On the '04 5.4L, the CHT sensor is used by the PCM to "calculate" coolant temperature, and logic in the PCM is very extensive concerning CHT. It runs an internal diagnostics routine at the startup and literally "re-calibrates" the CHT every drive cycle. EOT (Engine Operating Temperature) is "established" by this sensor. That parameter effects much of what the PCM does. It will even implement a "limp home" mode, alternately shuting off half the injectors/COP's under overheating conditions to try to protect the engine. An excellent article about the CHT and diagnosing it is available at:


http://www.searchautoparts.com/motor...ure-cht-sensor


I know you didn't mention any overheating symptoms - but if the PCM was getting a STUPID high reading from your CHT - IMHO you would have a rash of other symptoms including an MIL, several possible codes and even ragged engine operation (limp mode) if the CHT is failing somehow.


I got my 'hands on' education on this sensor for an entirely different reason. I was trying to sort out live OBDII readings from the PCM to create a custom guage on my OBDII code scanner program (Torque Pro). The sensor I was accessing (PID# 221685) turned out to be the CHT. There's a good picture and discussion about that effort on the Torque APP website at:


http://torque-bhp.com/forums/?wpforu...topic&t=5657.0


I do not propose to know what is causing your problem. I lean toward some problem in either wiring from the ECU to cluster or the cluster itself, but (based on what I know from the above experience) I would not just TRY changing the CHT sensor. Honestly, I would recommend getting scanner readings of actual PCM output from PID# 221624 (CHT in Deg. C) and PID# 221685 (CHT in volts 0-5v).


Hope this helps.


Best of Luck

Mod (Ret.)

So, our V8's in the 2004 to 2009 range do not have a seperate temp sensor and temp sender?

I ask because a Ford Ranger I used to own (3.0 V6) used a temp sensor for use by the PCM (what is being called on this thread as the CHT), and a seperate temp sender, used for the cluster guage reading.

F150Torqued

Hold on @Bucko


I am no expert on much of anything. Certainly, I do not wish to mislead anyone into thinking they could just screw a pipe plug into their temperature sending unit hole and everything would still work fine because their truck's Cylinder Head Temperature sending unit would handle it. Lol.

My truck is an '04 5.4L Triton. I know "IT" does not have a water temperature sensor. I do not know about a 3.0 V6 or ANY other year model, F150 or otherwise, or nothing! (My disclaimer - I don't know nothing!) I don't even know where the instrument panel water temp gauge gets its signal from...... But I have to "assume" (watch that one) it is driven by some signal (either serial, digital, or analogue or something) from the PCM because there is NO water temperature sensor on the 2004 F150 5.4L 3v Triton engine or radiator or water jackets.


But the @bushwicbill truck is the same model and engine as mine and I really didn't want him to go changing the CHT censor without really checking it out first - because it is a bitch kitty.


By the way, I love your Avatar!

Mod (Ret.)

I agree! I was only curious if the V8 engines were like the smaller Ford brothers in the way of having two seperate sensors/senders. I guess to answer my question, I'll be doing some googling, and/or checking the Ford factory repair guides.

bushwicbill

[MENTION=170523]F150Torqued[/MENTION] Thank you for the information. I will definitely look into it further before i take the plunge. I really don't want to do any unnecessary work if possible.

I have noticed over the past couple of days that the gauge is dropping. Now it is showing at half before i even put the key in. Everything is operating as normal, no warning lights or issues as i drive. The gauge does work just never bottoms out if you know what i mean.

Again thank you for the info. As soon as i find something out i will let you know. The way my schedule is right now it will be awhile before i can.