I agree with your sentiment when comparing a three state coolant temperature light to a true coolant temperature gauge, however, with the exception of some high-end exotics, I don't know of a single car that came from the factory since at least the mid 1990s that had a true gauge. Virtually every car since then has what I call an "Idiot Gauge" that is slaved to the OBD-II system, and while said gauge will gradually rise to the "normal" range following a cold start, it will stay there in virtually the same exact spot, year round, pulling a trailer up a steep grade in the dead of summer or descending a long grade in the middle of winter. That is with one exception; if/when things get too hot in the engine bay, said gauge will literally rise from "Normal" mode to "Oops! Too effing hot!" mode in a matter of seconds.

With that in mind, I really don't see a difference between a three-state idiot light and an idiot gauge.

 

The three stage light would be better than nothing. Apparently the 2010 Mazda3 simply has no indication at all of engine temperature. I wonder if a retro-fit is possible?

 

My reading of the Owner's Manual indicates the 2010 Mazda3 has a two-state light:

1. Off = Sub-zero through "normal" operating temperatures
2. Red = Too friggin' hot!

I kinda sorta doubt that a three-state light would be easily retroable to your car.

 

I'm sure you're right. We'll just have to live with it, but that red light usually means that you've already cooked something.

 

Unfortunately that's how modern temperature gauges work as well. They indicate "normal" for like ever, and then when something goes wrong they continue to indicate "normal" until all of the sudden, they swing the needle from mid-range all of the way to "HOT!" in a matter of seconds. I've never understood the rationale for that kind of programming.

 

Oh well, I have a Scangauge in my Tribute that I can move over to the Mazda3 if I need to do some trouble shooting. I'll just keep an eye on her coolant level and hope that she doesn't have any trouble during her commute. Thanks for all the input.

 

Scangauges are very handy.

 

Ah. good old first gen 04's like mine.. Nothing like a full temp gauge for me =) of course I like to know more than just lights what my car is doing. I added volts and oil psi to my pillar. I don't want to look at the red dripping canister if my oil is too low for some odd reason.

 

The thing is, you have an OBD-II car, and as such, you have an "Idiot Gauge". If ever something goes wrong with your car, the gauge will continue to hold the needle in the "Normal" zone until it's pretty much too late; then all of the sudden the needle will rise to the Hot zone in a matter of a second or two.

 

I agree shipo, they are idiot gauges which is the reason why i went to a true oil psi and volt gauge. I figured i'd live with the idiot gauge then put in a "real" one. I guess I was lucky when my thermostat went out it was stuck open so in the winter my gauge never moved lol. However, from other people's problems my CEL came on before noticing the "temp" gauge