Hello, new to all this forum stuff but, I do have an explorer, Sport trac v8. And it’s been fluctuating in the temp gauge on dash, but showing no signs of heating. It has been burped, all water components are new, radiator, thermostat, pump, CHT Sensor because my model and year truck/motor did not come with coolant temp sensor, but I did install my own temp sensor on top radiator hose. Which always reads 190-199. But. Replaced CHT sensor. Ford mechanic got my motor hot for putting in the wrong thermostat. The truck does not leak anything. Very very low miles. Just temp gauge fluctuates. And my water is reading basically not hot. Dunno if it’s the dash cluster as a whole or if it’s a wiring issue. But it works fine. Just sitting in traffic from time to time it will read like it’s getting hot. But no temp light no anything. And it’ll go back down once I take off. Don’t understand what is going on. Another ford mechanic at a ford dealership said. They experimented with those engines for a long time. And you are most likely chasing a ghost. But I can sit in my drive way in park or in idles and the temp won’t move a bit close to hot.. Only when I’m behind someone or in odd places. Any idea what it could be? And also any idea where I can get a programmed dash cluster to replace it? Dunno what I’m missing or if I’m missing anything.
Thanks.

 

Locate C107 (CHT) above, you can see it goes to C192 and S105 (Splice), then back to the PCM So locate them below and disconnect and clean them using 91% isopropyl alcohol (pour into a spray bottle and spray). Also check all the wiring, replace if needed.
The ECT appears to be for 4.0L V6 only.
If you look at below diagram and locate C104 (EOT), you can use your scanner or OBD2 adapter and retrieve the reading in a cold start. The temperature of your CHT should rise much quicker than EOT, to reach let say 200 degree F, CHT in 5 minutes vs EOT in 10 minutes. If not, there could be a problem with your thermostat (stuck open) or non-OE opening temperature or even problem with your fan clutch.
It looks like your temperature gauge on cluster gets its reading from CHT, indirectly. And replacing a cluster probably doesn't help, so don't waste money at this point. If you must replace it, you can remove just the temperature gauge from another one and replace yours, not necessary the whole cluster. The temperature needle, when fluctuating, 90% of the time you have a bad/broken/short wiring. The CHT should last the life of your vehicle, but the wiring is not.

 

I really appreciate this. This is something worth looking at.

 

Before condemning anything you need to verify the required power is available to components.
If the power available fluctuates,the readings will fluctuate also.
You can play hunt and poke and you might get lucky. There are certain things you need to verify and once they are verified, you can follow a diagnostic path and locate the cause.
What kind of test equip do you have to use ?

 

No I don’t. I’m not necessarily looking for an open end. I’m kinda looking at just getting a new instrument cluster for the most part. It’s reading/ getting power. It’s never not, worked. The problem lies sometimes just sitting a random moments the temp gauge goes up at bits at a time, until it gets about (3/4) of the way up, sometimes pretty close to all the way but no lights come on, but will cool down once I get to moving. So it’s not like shutting down or anything. It’s acting like more or less. It has a short somewhere from my CHT sensor to my pcm or dash. Either way my coolant is not getting hot. So it’s just a confusing situation.

 

You might consider the following,

What else is happening when you increase engine speed ? THE charging system increases output and raises system voltage and now the readings seem to stabilize.

Keep in mind that increased power could be overcoming a poor connection in the system.

Many times in the process of "Replacing good parts" that connection gets moved around and the problem disappears ,,,,TEMPORALLY !

 

Nothing like that is happening, only thing going on is the temp gauge on the dash acts up while sometimes sitting In traffic, or if I sit behind someone for a lil too long. It’ll go back down once I take off but I can sit in my driveway and let it idle and it won’t do anything, I can sit idle in 90 degree weather and it won’t act up it only doesn’t when I sit behind someone or at a random time. Most times it won’t do it, I can’t make it do the issue purposely just sitting somehwere. But everything has been replaced in the truck multiple times just out of curiosity and I have found fault products like thermostats and clutch fans. But I have replaced it all, even replaced the CHT sensor. But I asked a ford mechanic about my issue and he said if no temp light comes on when it gets close to hot or hot period, in the dash. And it will go back down while you drive, and you have no leaks or anything of that nature. That you possibly are chasing a ghost, or a potential short in the wire OR, most likely. A short in the dash cluster. Because the dash cluster works just fine. But temp gauge acts like it’s getting hot. But it just simply is not getting hot. Or else it’s throw a light. Which it hasn’t. But I’m looking into trying to find a place that sells dash clusters for my model truck possibly. Just a oddball thing going on and it’s just bugging the “far” out of me. But I do apperiate the comment though.
Was also told that these specific dashes that the f150s and sport tracs had had some kind of recall on them at some point? But known to be defective.
so now I’m to the point to where I’ve done all I can do. Now it’s either a new dash clusters or figure out if a wire is loose or broken, worn. Something. And that’s what gets me. Because it functions like it should! It just like. Doesn’t just shoot uo in temp, it like slowly makes it way up, like it’s tapping its way up to hot.