Toyota Yaris Hybrid Sometimes can't use EV during short trips

[Myn0k]

Hi there,

I love my Yaris Hybrid, but recently I've noticed an odd thing, particularly during the school run/first drive in the morning.

If I turn on the ignition and the car is at full EV charge, I drive off and stay within 30MPH - but occasionally it absolutely refuses to go into EV mode, despite full charge and under 30 MPH.

Then after dropping the kids off, I get back into the car, and lo and behold - EV mode works! So it's like I need to do a mini drive first, stop the engine, then get back in a second time for EV to work.

Is this normal, is it because the engine needs warming up first? I tend to keep my car in ECO mode.

Thanks!

Rob

[Bozz]

10 minutes ago, Myn0k said:

Hi there,

I love my Yaris Hybrid, but recently I've noticed an odd thing, particularly during the school run/first drive in the morning.

If I turn on the ignition and the car is at full EV charge, I drive off and stay within 30MPH - but occasionally it absolutely refuses to go into EV mode, despite full charge and under 30 MPH.

Then after dropping the kids off, I get back into the car, and lo and behold - EV mode works! So it's like I need to do a mini drive first, stop the engine, then get back in a second time for EV to work.

Is this normal, is it because the engine needs warming up first? I tend to keep my car in ECO mode.

Thanks!

Rob

Hi Rob, I believe you have already answered your own question. 

[preperationlaunch]

The Yaris has several warmup stages it goes through.

What you'll find is that it'll be running the engine at a high-idle when it's cold, but using the electric motors wherever it can. Once it gets to certain temperatures, it can start using EV mode etc. more.

You'll also find it'll run the engine more if you've got the heaters on, to warm the coolant up.

The following is pinched for the Gen3 prius, but it's very similar in the Yaris.

Quote

S0:

it is from power on until the ICE starting for warming up (approx 12 seconds)
you can enable the EV-Drive Mode during this S0, if the conditions are allowed so (refer to your owner's manual)
the EV-Drive Mode can not be turn on when (1)the temperature of the hybrid system is high (ie; the hybrid battery is above 46C), (2)the temperature of the hybrid system is low (ie; the hybrid battery is below 0C), (3)the hybrid battery charge level is low (three bars or less), (4)the windshield defogger is in use or (5)the engine coolant temperature is below 0C (maybe 20C on the US Prius)

S1a:

when the start coolant temperature is below 40C, the warming up starts and continues for approx 50 seconds after S0.
you can not enable the EV-Drive Mode during this S1a.
the ignition timing is very late, after the top dead center. therefore the engine does not have enough power to drive Prius or charge battery.
basically, Prius can not use the engine power when you drive. Prius is driven by battery power and the battery is discharged.
it is good idea to drive slowly or stand still warming up in this stage.
when the start coolant temperature is between 41C and 60C, Prius is in this stage, but the engine does not start automatically.
when you press the accelerator (including driving), the engine starts and runs for approx 50 seconds or until the coolant temperature reaches 65C. the ignition timing is very late too.

S1b:

this is an extended warming up stage.
you also can not enable the EV-Drive Mode during thisS1b on Gen3. (you can enable the EV-Drive Mode on Gen2)
the ignition timing is now normal, and the engine is able to provide power and charge battery.
you are now ready to drive without any penalty of battery discharging.
( A ) if the the coolant temperature is still below 40C after S1a, the warming up continues until 40C.
( B ) if the the coolant temperature is between 40C and 50C after S1a, the warming up continues until 50C.
( C ) if the the coolant temperature is between 50C and 60C after S1a, the warming up continues until 65C.

S2:

after the S1a or S1b, Prius goes to this stage.
Prius acts as normal until the coolant temperature becomes 70C (going to S3).
The EV mode speed is limited below 10 mph on the NA Prius.

S3:

when coolant temperature becomes above 70C, Prius goes to this stage.
Prius acts as normal, but Prius requires an "idling check ceremony".
The EV mode speed is now allowed up to 25 mph on the NA Prius.
the "idling check ceremony" is done during an accelerator off gliding for several seconds on Gen3. (on Gen2, Prius needs a complete stop or very slow walking speed for the ceremony)
the engine continues to run during the several seconds ceremony.
after the ceremony, Prius goes to the S4.

S4:

Prius now completed the warming up stages and in a full normal condition.
if the coolant temperature is above 60C on power up, Prius is already in this stage.
note: this is not a complete list yet and it is based on JP Gen3 Prius, therefore "subject to change" and may not apply other country's Prius.

 

[Rosgoe]

Try putting it into EV before the engine starts when you first start the car I do this when I just want to get the car out the garage it should go into ev providing there is sufficient charge in the traction Battery.

[TonyHSD]

1 hour ago, Rosgoe said:

Try putting it into EV before the engine starts when you first start the car I do this when I just want to get the car out the garage it should go into ev providing there is sufficient charge in the traction battery.

Correct, I do the same but this one to work i need to switch off the heater fan. 👍

[Myn0k]

Thanks everyone, super helpful!

[Cyker]

I noticed mine doing this more often in the mornings, but have realised it's just because it's colder in the mornings now, and the car is trying to warm the engine up more to supply heat into the cabin!

If the engine is running when I'm not expecting it to, I found hitting the Off button on the HVAC, or lowering the temperature, will immediately turn off the engine again.

 

[TonyHSD]

Even when the engine it’s running to heat up the cabin or while in warming up stage  the car still gets propelled by the electric motor and you can feel acceleration but engine rpm stays the same  the ice works as generator for electricity and heat. 👍 still better and more efficient than any ice only cars.