Engine temperature gauge problem?

[bowtiefreak]

So all of a sudden the temperature gauge is showing a lower than usual temperature. Like from one day to the next and it has remained that way for a week.

Usually indicated about 200-210
this day 175ish (we all now these gauges suck and are a reference point but still)

I replaced the thermostat (195) and temperature sensor. No difference.

I am worried the ECU thinks it is running cold and is going to play with fuel / air ratio

Why is the gauge indicating lower than usual? is it bad?

I have plenty of heat, it makes me feel like I am melting.

I'm stumped, ideas?

 

[laredo1307]

That's a good question. My Tahoe has always run at around 160F. When I changed out my radiator and waterpump I put a 180F T-stat in but still the dial reads the same. Maybe it is at 180 but the dial is slightly off. Anyways, I've never seen my gauge fluctuate except when I had a crack in my radiator.

 

[bowtiefreak]

my gauge does move, just not to where it used to. It spiked up once to the 210 range but right after I swapped the t-stat and sensor. then never again. The sudden change is why I worry

 

[bowtiefreak]

There is a temp SWITCH on the drivers side head...feeds to the gauge. New switch just went in. need to drive ans see what happens

 

[bowtiefreak]

The temp switch didn't do the trick either.

What's next?

 

[SouthernHoe]

All the Vortec V-8s and V-6's have run where you are describing normally. If mine gets to 210 something is wrong. It did just recently and I realized I had a leak and it was low.

 

[bowtiefreak]

both my trucks have always run about 200...t-stat is 195*...when it dips too low there is an issue. Last time it did this was a bad thermostat.

This was a sudden change from one day to the next is why it is in question. I've owned my one truck for 14 years and I know it pretty well. this is a weird problem.

Where is sunlit?

 

[SunlitComet]

The dash guage and the pcm use two different sensors. What does the pcm see, by means of a scanner, as it's reading when you see the dash guage dip as well?

Sent from my SPH-L720 using Tapatalk

---------- Post added at 02:53 PM ---------- Previous post was at 02:50 PM ----------

You can test the guage as well with a variable resistor with a range of 90 ohms I think it was.

Sent from my SPH-L720 using Tapatalk

 

[bowtiefreak]

Both sensors are new. Going to try to get a scanner on it tomorrow.

Thanks

 

[Tbruz]

Sunlit,
Can you post the procedure to test the temp gauge using the resistor?
Thanks
Tbruz