Red triangle going downhill

bring it to another garage with the proper equipment to read the codes on a prius. are the tires the same size?

 

To be honest to me it seems like you're low on oil up inclines around turns spirited driving etc with not quite enough oil in the car can make that light bounce on and off also in this model coolant issues can cause the same problem The coolant is more tricky to track down so with your car warm you get out of the car you have to have that silly piece of plastic that covers your radiator cap and your fans removed so take that off get the car warmed up get back in the driveway crack the radiator cap just enough to blow off the air you'll hear the air noise You might see a few drops of coolant run down the side of the radiator neck once the pressure is vented remove the cap If you don't see radiator fluid at the very top of the filler neck something's going on so now you take a bottle of water or red coolant and you start adding some to the filler neck and when it comes up to the very top of the filler neck you stop pouring. Now you watch the level of the filler neck you all of a sudden see some air bubbles plop plop and that coolant vanish is down into the radiator and you can't see it pour some more in do this until that stops and the level stays at the very top of the filler neck right at that hole where it's going to drop in and go to the reservoir this may take over a quart of coolant to get you to that level I have a car that does this every 8 days No one can find the coolant. If I leave it longer than 8 days when I'm driving down the road I start seeing the triangle Go on and off and on and off when I see this on my '09 when I get home I do repeat the steps above for filling the radiator I always add close to a quart and then I close it off drive another 8 to 10 days No one has been able to find where the coolant is going I work on my car's extensively I can't find any leaks I don't see it burning up internally I never have any misfire codes or anything like that for any coolant leaking into the cylinders so on and so forth there may be a microscopic leak in a hose or the radiator but I'll be darned if we can find it and I'm pretty good at finding this stuff I'm not willing to just replace all the hoses and rubber just because most of it looks pretty new and and pretty good shape and not becoming permeated or destroyed so they stay they all pump up to pressure nicely The car warms up well etc check those things and see what you got I'm betting on the coolant.

 

You are dangerously low on oil!
Stop driving immediately.
Check you oil level an post a picture of your dipstick here.
Buy 2-3 quarts to refill as needed. You may even need more.

 

Guess they previously Didn't check the oil.
Glad to hear you engine didn't get destroyed.

The symptoms you described were classic signs of DANGEROUSLY LOW oil.

 

Just the red triangle alone could mean failing Hybrid system, Brakes, Electrical, anything critical of importance. To simply say it means "oil level low" is wrong. There's an oil can light (yellow) that will flash or come on intermittently when the pressure and level drops below the sensor. (during similar driving situations like you described).. I've never seen the triangle for oil being low. At that point it should have already thrown a rod through the block.

 

I was referring to the way/times in which the red triangle appeared.

He said

The red triangle appears when...
* I drive down a hill at 50mph and I've taken my foot off the gas pedal.
* I go round some corners.
* When I drive up a shallow ramp to a freeway and there's a slight tilt downwards of the road to the left.

 

Yes, and each of those times (if oil level was low) the actual oil light like I mentioned should have flashed or come on and not just (or ever) the red triangle. You made an assumption that was incorrect and got lucky.

 

There have been other reports here of the master warning triangle for low oil pressure indication just as ericbecky described, where the warning has flashed but not set a corresponding DTC.

I've never seen a low-oil-pressure indication in my car (never let it get that low), but I guess it wouldn't be hard to go ground the sensor line and note what happens.

 

Yellow Oil Can symbol doesn't set DTC's..it's simply an idiot light to tell one their oil is dangerously low. This is the primary notification, not the triangle. Triangle is the end game, user is indeed lucky it didn't blow up.

 

Super easy to check, without even getting a greasy arm reaching for the oil pressure switch, as the diagram shows that circuit going through the handy DA1 connector found in the fusebox, at pin 16. It's purple.



The low-oil-pressure switch is just a simple switch that is open when the pressure is ok, and grounds the circuit when the pressure is low. So all you need to spoof a low-oil-pressure condition is to stick a probe in pin 16 with a way you can ground it.



Good to double-check which way the pins are numbered: pin 16 is fifth in its row if you start counting at the end that is red, black, red, black. The fifth pin counting from the other end also happens to be purple; don't mix 'em up.

I have this old-school tool sold as a "remote-start button": it's just two big red clamps and a length of wire, leading to a big egg-shaped thing to grab in your hand with a big thumb button on top. It looks like a cartoon villain should use it to detonate bombs. It was originally to clamp to starter-solenoid terminals so you could crank an engine while standing in front to watch it. But of course it works for any job where you want to push a button to connect a thing to something else. Clamped here between a nice grounded nut and my pin 16 probe, it reaches nicely into the cabin where I can watch the dash in comfort and use my cartoon-villain thumb to make "low oil pressure" happen and not happen.

Every time "low oil pressure" happens, there is one high-pitched beep about half a second long, the master warning triangle lights up, and the MID displays LOW ENGINE OIL PRESSURE. (My MID does not really have a diagonal blank bar across it; that's a thing between the MID refresh rate and my phone camera's shutter speed.) When the oil pressure is back, the triangle and MID message go away.



No "Yellow Oil Can" symbol is anywhere in sight. Indeed, the warning-lights page in the owners' manual also does not show any such light.



There's nothing especially "end game" about the master warning triangle here; it lights right up every time the oil-pressure circuit is grounded. The oil pressure switch only does that one thing; there is no way it could somehow indicate "kinda low" and also "end-game low".

Of course, as gets regularly pointed out here, any time an oil pressure warning is given is a bit of end-game; without oil pressure, the engine is eating itself a little every time. Nobody should rely on the oil pressure warning to decide when to add oil; there's a dipstick for that.

My tire-pressure light is on 'cause I still haven't replaced the transmitter Walmart busted changing a tire on my road trip.

 

You are showing evidence for and of a YELLOW triangle caution light, which still doesn't signify anything to anyone about oil pressure or oil level being low. There will also be a message in the warning box that comes up and tells you that your oil pressure is low in words (for those who don't understand the idiot lights).

 

This is what you should see flash on and off depending on the oil pressure and level.

 

Yes, the master warning light has changed its appearance over the generations. In gen 1 and gen 2 it was a red outline triangle with an exclamation mark. In the US gen 3 liftback (2010 for sure, anyway), it is a filled yellow triangle with an exclamation mark. (People do still tend to call it "the red triangle" out of habit, when they're not calling it "the triangle of death". But this is one reason it's better to just call it what Toyota calls it, the master warning light, and leave off the quibbles over its exact appearance.)

In the Prius v wagon, as you may have noticed, it's not even triangular anymore, but is a car with an exclamation point, and has been renamed the hybrid system warning light.

The OP here is in England, and has called it a red triangle. For all I know, for a 2010 in that market, it could be red.

The only connection it does have to low oil pressure is that it comes on every time that is detected. Of course, it also comes on for a couple hundred other reasons that are distinguished by DTCs stored in the power management control ECU. So no, you can't always assume it's about the oil.

On the other hand, if it comes briefly on when cornering or taking hills, goes out again right away, and leaves no DTC behind, you aren't making a bad guess if you guess oil. Of course you should notice the big words LOW ENGINE OIL PRESSURE too, but not everybody does. People sometimes get fixated on the lights.

Yes, that's seen in the demonstration above, and also in the repair manual.

It would be more helpful to mention the source of the image you attached. This is the gen 3 liftback forum, but that does not seem to be from a gen 3 liftback owners' manual.

The corresponding display in OM47668U.pdf (2010 liftback) is on page 497 (491 of the PDF) and looks like this:





On the other hand, if this were the Prius v wagon forum, it could be appropriate to use this, from page 443 of OM47674U.pdf (2012 v wagon):





But this forum is for the gen 3 liftback.

 

Yes I was referring to the dashboard cluster for the liftback. And yes, ErickBecky still got Russian Roulette lucky based on the description the OP gave by saying it was oil related when, like I mentioned could have been a multitude of things. And no, the YELLOW triangle warning does NOT come on every time the pressure is low (due to subsequent low oil level in the pan). I've witnessed this on several, if not many Gen 3 "liftbacks" and had dozen's of oil burning cars report the exact same thing. Only ones that have already seized or blown a rod through the block will typically have the death triangle at that point. (Not to say that it COULDN'T come on in conjunction WITH the pressure light and sub-subsequent error message on the dash).

 

You have not addressed the fact that you attached an image that is not from the liftback owners' manual, showing a warning light that is not shown in the liftback owners' manual or present on the liftback gauge cluster. (2010, anyway)

You have not identified what owners' manual your attached image did come from. Because it shows the carbang-shaped "hybrid system warning light" instead of the triangle-shaped "master warning light", a v wagon owners' manual could be a possibility, as the v dash lights are like that.

As Eric already explained, it lights up for a multitude of things that set DTCs, and also with the low-oil-pressure signal, and when it is only on briefly, without DTCs, and only in circumstances where g forces are moving the oil around, "oil" is a fair guess. It is still a guess, but many questions on PriusChat attract less well-supported guesses.

Post #13 reports a simple demonstration where it comes on like clockwork whenever the oil pressure switch circuit is grounded. There is only one oil pressure switch with only one circuit, and that's the one way the car detects low oil pressure.

Post #13 gives enough detail for anyone interested to replicate it. No one needs to take my word for anything.

In other circumstances I could be willing to take your word for that, but in view of its conflict with what #13 demonstrates, something more reproducible would be better.

 

Perhaps it's on the 2012+ cars? Anyone chime in here. I've seen it and not making this up.

Then maybe of the dozen or more vehicles I've seen it on, that yellow triangle was not operating correctly or the bulb (diode whatever on the cluster) was burned out. The main take away for non mechanical lurkers here is...A) Don't own a 2010-11 for sure and probably not a 12, 13 or early 14 for that matter due to oil burning and B) If you happen to have one of these said vehicles, please check your oil at least weekly if you drive the car every day so you don't see any lights or triangles and have to post here about it.