Yaris MK1 coolant lights

[Tom Kay]

Hi, I bought -03 1.3vvt to my wife and was wondering should the blue coolant light turn on when ignition is turned on ? The red light only turns on, and the temp outside is below freezing. Does the blue light get its info from the same sensor as the overheating light ?

[MRichards]

As far as I remember (I'll check my car out when I leave work tonight), the blue coolant light doesn't come on (or doesn't stay lit at least) when the ignition is on but the engine isn't running. This is correct. When the engine starts, then the blue coolant light should appear (and stay lit) as long as the car is cold. As long as the red coolant light doesn't come on while the engine is running, there's nothing to worry about :) My blue light usually goes away after a few minutes of driving (less if I have time to leave the car to idle for a few minutes before driving it).

[Tom Kay]

Yep, but mine blue light has never lighted. Today was -5C so I think it should have come on. I think there is only one temperature sensor, near thermostat and depending the value ecu decides which color temp light is light if none, and if the cold light is not lighting up when it is supposed I can't trust that red light works when overheating.

Need to check the sensor and its harness...

[Cyker]

Could also be the fuse or the bulb for it has blown?

But yeah, should be on for at least a few minutes when you first start using the car... unless you're flooring it and screaming off the driveway everytime!! XD

[Tom Kay]

Broken bulb, thanks 

[Cyker]

Phew, that's good news - Nothing too expensive then!

Was it hard to change?

[Tom Kay]

Noup, heater knobs off, under there is 2 screws, jiggle/pull the instrument cluster collar off, 4 screws in the cluster and there you have it.

 

Easiest dash to take a part.

[mrpj]

Just for a bit of trivia, the low temp light extinguishes at 45degc. Checked via OBD2 socket.😁

[MRichards]

21 hours ago, mrpj said:

Just for a bit of trivia, the low temp light extinguishes at 45degc. Checked via OBD2 socket.😁

So I guess the car still needs gentle driving despite the light going out (45 degrees isn't warm enough to start using plenty of revs)?

[mrpj]

On my car the low temp. light is green.

I would much prefer it to be blue, i.e. blue = cold, red = hot. Green suggests all is well. No, it's not well, your engine is too cold!

I wouldn't and don't use "plenty of revs" until working temp., 90degc, has been attained, or very nearly.

[MRichards]

1 hour ago, mrpj said:

On my car the low temp. light is green.

I would much prefer it to be blue, i.e. blue = cold, red = hot. Green suggests all is well. No, it's not well, your engine is too cold!

I wouldn't and don't use "plenty of revs" until working temp., 90degc, has been attained, or very nearly.

I wait quite a while after to make sure its nicely warm (without a gauge like in most cars in can be difficult to know when) but just wanted to make sure I wasn't doing this if it wasn't needed :)