Main Warning Light ( Red Triangle) Keeps Coming On.

[Steersy]

I have a 57 plate Prius t spirit which I have been very pleased with.

Recently the red triangle warning light has come on while trying to start the engine. Pressing and holding the start button seems to clear it, and usually the engine ready light then comes on.

I have also had a warning message regarding the hybrid drive stating to re apply the parking brake on a level surface. This has only appeared once.

The rear discs and pads have just been renewed, could this be linked to the warning, as it has not appeared before.

Any advice wlcomed

[johalareewi]

Could be the 12V Battery needs replacing. Strange things start to happen when the 12V Battery is on the way out.

[timberwolf]

+1 to check the 12V Battery. It's not a bad age if it is still on the original.

Unlikely to be the rear brakes themselves as they are purely hydraulic (no regenerative braking on the rear).

Indirectly, I wonder if the mechanic may have inadvertently "helped" to use up the 12V Battery whilst working on the car?

[Chris Dance]

Agree with others 12V Battery is on its way out. Cannot see how working on the brakes would cause it unless the garage chap had your car radio or interior lights on with no engine running.

[PeteB]

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I have also had a warning message regarding the hybrid drive stating to re apply the parking brake on a level surface. This has only appeared once.

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This can indeed be due to the 12v Battery being low, but can also happen id the car was not quite stationary when P was selected (or OFF). The Gen 2 would allow P to be selected up to 4 mph (which could be accompanied by some serious rocking if near the top of that range).

Is the 12v original?

What sort of mileage has the car done?

[Steersy]

Could be the 12V battery needs replacing. Strange things start to happen when the 12V battery is on the way out.

Thanks for the reply. Will check out the Battery.

[Steersy]

Thank you for your replies, it points to the Battery as you all said.

I remember that just before the first time it happened I could not unlock the car with the remote, and when I used the physical key, the alarm went off.

In reply to the question regards the Battery it is the original so will look to get it changed.

Thanks again.

Dave

[kithmo]

I had this message once, on the Gen 3, when one of the doors wasn't fully closed.

[Steersy]

Hi. I had wondered about the doors. They all seem to be shut but I suppose one of the sensors could be faulty.

I had a look at the diagnostic page for the Battery and this stated the charge to be 14.5 volts, which I wasn't expecting, however I have noticed that the LCD panel has taken a while to come up to full brightness so still think I will get the Battery checked.

Thanks for your reply

[Grumpy Cabbie]

East diy way to check your 12v is leave the car overnight and in the morning get in and turn the car on to Acc mode (NOT Ready mode) and then wind all windows down together and then back up. If they go really slow and your interior lights go dull, then your 12v is probably on its way out, esp if it's the original. Compare the above with the car in Ready mode and if they then go up and down nicely you know the issue.

The Prius 12v is easily changeable with a main dealer for about £100 fitted. It's usually a fixed price item, though depends on your dealer. It's also a weird thing and you're unlikely to get a matching item from Halfords. The official 12v has a vent as it's in the cabin part of the car (well the boot, but it's not under the bonnet).

At least get it checked before the cold weather hits!

[PeteB]

Hi. I had wondered about the doors. They all seem to be shut but I suppose one of the sensors could be faulty.

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The boot can also sometime be almost latched but not quite - if the boot light is on the auto setting that can cause it to stay on, but the car would refuse to lock with the usual bleeps.

[Steersy]

Thanks...I will give it go