97 F150 Temp Gauge Problem?????

[jschade]

OK ladies and gents I really need some help. My temp gauge goes from below normal to pegged instantly and the engine is not overheating. I've checked both temp sensors on the manifold and both connectors, they are fine. I've replaced the thermostat. The head gasket is not leaking, antifreeze level is fine, stays full. When the temp pegs the overheat light comes on then a couple min later the engine starts powering down (shutting down cylinders overheat mode). If I turn off the engine and restart it goes back to normal then repeats minutes later. If I turn off, then unplug both both sensors the temp gauge pegs again but does not cut off engine and will run fine. I have ran it 300 miles like that will no problems. I just can not stand not having a temp gauge. I'm pretty sure it is an electrical problem or computer problem. Has anyone ran into this problem, any solutions. Yes I know get a aftermarket temp gauge and don't worry about it, but I don't want to stare at an overheat light forever. Is there anyway to shut this temp gauge off without shutting down the entire dash??

[Bluegrass]

First thing is to scan for codes set when the condition exists.
This will give a clue to the issue and what to do about it.
The dash gage and lamp is only reporting the fault
Fix the cause and the dash actions will go away..

[jschade]

Thanks, there is no check engine light on will a scanner still read it?

[Bluegrass]

If your sure the motor is not overheating then all the cooling system work was unproductive.
Seems like only the coolant gage circuit is in trouble.
If you have the full electronic dash, it has it's own micro processor that runs all the functions with inputs from the PCM and some individual sensors.
The CHT will be monitord by the PCM . If there is an issue there, then the PCM will react to it seperately.
No codes would indicate only the dash indicator circuit is in trouble.
You just have to sort and seperate where the real fault is.

[nkolessa]

I am having a similar issue with my 197 f150 4x4 4.6L. I was having gauge issues (Oil pressure and voltage). I swapped out the oil pressure switch and found I had a bad ground. Anyways, upon restart those two were fixed but the temp gauge was pegged. UGH!

I replaced both the temp switch and the coolant temp switch, still not fixed. If I pull the plug the gauge reads Cold., If I short the temp connector it reads hot. The factory service manual says it is a switch issue... tried 2 new ones no luck.

any ideas?

[nkolessa]

I should add that I get no codes...just a temp gauge pegged to hot. This is on a cold engine too.

[jschade]

I finally fixed mine there is a total of 3 sensors 2 on top of the manifold and 1 underneath the manifold. u can access it by removing the alternator and reaching into the valley under it. It can he done cause this is how I replaced mine if standing in front of the truck facing the engine it will be on the front right side