Temperature gauge

Two things to keep in mind:
.
1> Pilots are perfectly capable of keeping track of many gauges
at once, so the "distraction" argument is irrelevant.
.
2> Many modern "gauges", especially in american cars, are just
for show, and are actually idiot lights. No bull. They either
indicate 0, or at threshold they come up to somewhere in the
middle, and the "idiot" part would be pegging the right side.
But they don't actually indicate a linear quantity. This isn't
true in all cars and I can't give you a list of "fake gauge"
vehicles offhand, but I have it on pretty good authority that
this kind of fakeout is fairly common.
.
_H*

 

Bah,

Completely different circumstances.

Pilots tend to have significantly more training than the average driver.
Pilots tend to have significantly less obstacles than the average driver.
Pilots tend to have a significantly greater following distance than the average driver (both in front and behind).
Pilots tend to have more indicator lights than the average driver.

I can come up with those 4 having never been a pilot. Maybe some of our pilot PriusChat members can chime in here and add any other significant differences in circumstances (or correct me if I'm mistaken)?

Interesting to hear though that some of those making, "I've got to have a gauge!" comments may be using binary indicators without even knowing it. It kinda brings a smile to my face.

 

I love to drive, and I love cars. I'd rather watch the road than a tach, it just feels safer.

Gas burners like to watch a tach. Personally, I'd rather know how much power is being drawn from or pushed into my HV battery. This information seems much more useful in a car where I have so little direct control over ICE RPM.

I guess this means I'm not a "car people".

 

I was about to post my first question on this forum and it was about the temperature gauge as well.
I am not planning on racing either and, completely opposite from bnaccs, my interest is around winter mornings (easily -10C).

I use a timer for my block heater and I like to "see" how it helps. Before getting the Prius I was driving a Matrix to work (still have it). I could "see" how faster I got a "decent" coolant temperature after start driving to work when using the heater.
Now, with no gauge, I only "know" that to use the heater is the right thing to do.

 

I think that Toyota deliberately did not put a temperature gauge in the Prius. Here is why:

Traditional car:
In a "normal" car, the engine is always running. With use of a thermostat and radiator fan the coolant temperature rises to the operating level and stays their. Every car I have had (one exception, a 1966 MG warms up to an operating temperature and stays put at that temperature. I will give you an example. My 1990 Honda Accord would warm up and stay with the red needle just short of the middle line. One day I noticed that the tempeture climbed somewhat. This continued to get higher and higher. I needed a new thermostat. I replaced the thermostat and the temp went back to where it was before. This is "normal".

Prius hybrid operation:
Via the scanguage, (recently installed) the temperature is all over the place. At start up it rises fairly rapidly up to 170-190. But, if there is an extended gliding period or engine off period, it immediately drops to 150 or lower. This would display on a guage and cause a lot of people to question this. Compared to their previous vehicles, this is not normal operation and would cause a lot of questions. Normal hybrid operation is for the temperature to vary. The temperature goes up and down and does not stay put. This is why the engine runs more in winter so the heater will work. If the engine didn't run more, the heater air would also vary in temperature, again not a "normal" way people are used to cars operating.

I believe this is one reason if not the major reason why the temp guage is left out. I think that Toyota wanted to make the Prius as normal as possible for the average driver. The last thing they wanted is for the average driver to think there is something wrong with the car, as the average driver is used to seeing the temp gauge remain constant once the car is warmed up.

 

People can't cope with all the instuments in their Prius now, some of them have trouble keeping an eye on the fuel gauge and they run out of petrol!!

 

I read a study once on aircraft gauges. It seems that pilots are trained to do a panel scan. The problem is digital gauges. An analog gauge gives a "relative" position, so that a pilot (or driver) can scan the panel, and understand the the gauges are in the "right place" ie, oil pressure ~50psi etc.

The problem with digital gauges is that the operator must evaluate the information, and determine if it is correct. Is 52 psi correct for oil pressure? Add that up for a significant number of gauges in a plane and you have overload.

I can't speak for fact, but I believe that is why many manufactures have gone back to analog display gauges in complicated situations. (I still don't like the digital speedo in the Prius. I don't care if I'm going 62 mph, or 59 mph, I just want to be going 60!

Icarus

 

I'm pretty sure the reasons given above for there being no temp gauge in the Prius is correct. I've tested the temp. gauges in my cars for years. They are non-linear. That is, they read cold until the car is almost warm then they move to "normal". When the coolant heats up they stay at "normal" until it's too hot, then they move up.

Once again, "Why?". Easy. The customers would often take the car back to the dealer if they saw the temp. gauge moving around as they drove. Most people think the coolant stays at the thermostat temp. It does not! It moves around a lot.

Get yourself a Scangauge II and see for yourself. In the Prius, the temp. moves even more than a "normal" car. In the winter Pearl struggles to get the coolant up to 70C in the city. It drops when stopped at lights, for example, even if the engine is still running.

 

It gets even better. Honda was known (and may still) base the oil pressure gauge on the tach. If the oil pressure was OK then the gauge would move up and down from the tach signal. Of course, if the oil pressure was less than sufficient then it would indicate zero.

My '97 F-150 had numerous bogus gauges. The voltmeter was always pegged at one spot no matter what the engine rpm (even if the engine was off and ignition on) or the electrical load. Same with the oil pressure. Never moved one iota from 3/4 indication when the engine was running.

Rick
#4 2006

 

I remember from years ago riding in a Chrysler product. I distinctly recall seeing the Ammeter click down and up with the blinker. Bet that one was accurate, unlike what's described nowadays.

 

Most likely it was accurate, but probably generated more service complaints from the uninformed than a "bogus" ammeter that would not accurately indicate current load.

Rick
#4 2006

 

I could care less about varying temps. I am more concerned with red area temps. But even with a Hybrid the temps would stay pretty constant with freeway driving, with city driving you would be correct as it would move all over the place. But still....a temp gauge is very important in letting the driver know when the engine is about to overheat. At the very least it gives you something to prepare for while you are driving.

 

Well, Im going against the flow here, but I think Toyota got this right - as the engine temperature vaies so much, and particularly as the temp would drop in stop and go traffic ( as the engine will run much less), rather than going up as in every other car then I think a temp guage might have drivers freaking out and thinking something was wrong.

 

I'm with you.

 

Why would anyone freak out about the temp as long as it doesn't go into the red zone? That is the only time you need to freak out.

 

I would bet it is pretty well 'damped' to avoid fluctuation rather than being real time. Probably more of an average temp over several minutes.

 

Actually, the temp does move around on the freeway too. On level road, not so much, but on even moderately hilly terrain it changes. On level roads the ambient affects the coolant temp - and unless you've ridden motorcycles you might think the ambient changes little. It actually changes quite often. But usually only by a few degrees at a time. I can see this on the Scangauge, but an automotive temp gauge doesn't show it (even one I've modified to remove the non-linearity). But climb a mountain pass, and you'd start to worry. Pearl got up to 110C on the way up a pass last summer. I think it boils around 120C (due to the 50/50 mix and the pressure). The car didn't "panic" (no lights came on, no buzzer sounded), but I started to wonder exactly when it would boil.