Cruise Control Triggers ICE?

I experimented with this some more. Last night with a warm battery and <90% charge I turned cruise control on and off numerous times, and it didn't seem to trigger the engine or do anything unusual. I tried DRCC with a setpoints below and above my speed, with and without cars ahead of me, and it didn't make much difference. I also tried standard cruise control (hold the cruise control on/off button for 3 seconds to activate), and there was no significant difference there.

This morning with the battery at 50 degrees F and 98% charge, cruise control instantly turned on the engine. I was surprised it happened with the battery relatively warm. After the engine warmed up, I switched to EV mode and each time setting the cruise control turned on the engine. The behavior was the same with non-DRCC, so that's good I guess. As soon as I dropped below 90% charge it stopped turning on the engine.

I definitely did see a blip of engine braking on Hybrid Assistant one of the times, but I was mostly watching the road and the EV light. I'll review the Hybrid Reporter graphs and see if I can find anything interesting. During that engine braking, the car didn't actually slow down, it was just the engine braking against one of the motors, and the overall power output was roughly coasting.

 

I know for sure, the Prime doesn't always behave the way I think it's going to or should. The only other suggestion I can think of ATM is try regular cruise instead of dynamic cruise to see if the car behaves the same, if you haven't already done that. Or try setting cruise at it's bottom end (28 mph dynamic ) while feathering the go pedal as you set cruise. Than raise to your desired speed using the stick and watching the MID and speedo at the same time. And get a feel for how the computer handles that.

 

That's so bizarre. How are you determining the ICE is on?

 

That looks like a bug to me. Change your main screen to the one with the car and electric flow on it, you can see if the engine comes on with that. (or the main EV light just to the left of there.)

I did some testing the other day but couldn't ever get the engine to come on by those displays, but I never look at the one you're looking at. (I use the HUD instead and I don't think that shows that little car.)

I'll see what that indicator says next drive...

Anyway, I still think it's bizarre, and it shouldn't do that!

 

That little car stays EV for me as quick as I can get to it, as the cruise control screen overlays it when I turn it on or change speeds, so I have to press the back arrow to see the HV display quicker.

 

It sounds like the engine isn't coming on for you. If it does, it will stay on for a while until it warms up. It's most likely to happen when the battery is cold (<40 F) and >90% charged, but it can happen other times too. Note that if you drive regularly the battery is probably always 10-20 degrees above the outside temperature, even the next morning, and if you plug in overnight the battery heater will keep the battery between about 34-37F minimum.

Hybrid Assistant confirms that the engine comes on when the EV "light" goes off. Sometimes the engine is on even if there's no power flowing from the engine. In rare cases the engine might be on for a short time even when the EV "light" is on, but it's not common.

 

Often while the engine is warming up it's just idling, so it's not charging the battery. So no power flow is shown on the energy monitor screen. It would still be helpful to have it indicate if the engine is running or not.

 

The energy monitor is just a dumbed down cartoon representation of what's going on. Hybrid Assistant shows much more detail (actual power levels for the engine and motors) and updates much faster. I've noticed that setting the cruise control causes a short blip, less than 1 second, of engine braking sometimes (negative engine power), for some reason. If the engine is cold and it runs even a little, the car will complete a warm-up cycle. I don't like the engine coming on, so I haven't experimented with this too much to find the limits of conditions when it will or won't start.

I think the engine coming on is definitely a bug. But I don't think the car provides enough information for us to troubleshoot the bug. Hybrid Assistant is a little more helpful, but without knowing why the engine comes on in the first place we might never know why this happens.

During the unintended acceleration scandal, it was revealed that there were millions of lines of "spaghetti code" in the car's programming. I think it's safe to say that Toyota doesn't have the best software. Their infotainment systems are further evidence (even if they are probably done by a different team).
Toyota Unintended Acceleration and the Big Bowl of “Spaghetti” Code | Safety Research &amp; Strategies, Inc.

 

For those not familiar with software engineering, "spaghetti code" means that the the flow of control in the code is absurdly complex, jumping forward and backward from one place to another, so it it is difficult to know exactly what it is doing, and very hard to get it to behave as intended. In well designed code, the flow of control is comprehensible, using established design techniques, and there is a better chance that it will do what is intended. I have been doing this kind of thing professionally for 45 years, and lost hair having to deal with spaghetti code.

 

Thanx for your theories guys!! Same thing happened to me with the exact same conditions 5 time this week.