[SmellyTofu]

Back in the old days, ACC could hold you at the set speed by braking/regen and/or engine braking. This was in fact a hybrid only feature never promoted from LS600hL through to Prius gen 3. A true set and forget solution.

However there is very little literature about the changes to its operation where if you’ve set a target speed, and you happen to be going downhill sufficiently to speed up, the dashboard that shows the target speed changes to an inversed display (white background on black text) of the set target speed and a warning beep.

I’ve not driven any other TSS2.0 (don’t work for Toyota anymore) to know if this is the new norm but has anyone had this experience?

 

[RAVDoug]

I've never seen this inverted display and warning in my RAV4 hybrid. When I've been on cruise control going downhill, it activates the regen braking (until the battery is fully charged) and engine braking. Maybe I haven't been on a steep enough hill -- this is from coming down I-70 after the Eisenhower Tunnel in Colorado, though, which isn't insignificant. I would hope it uses the brakes to control speed as well if engine braking isn't enough, but I don't know if I've ever reached that point.

 

[SmellyTofu]

You’ll need to find a steeper hill but it does moderate speed on gradients up to around -5%. Kinda runs away afterwards beeps but doesn’t try very hard to hold it back from creeping faster.

 

[RAVDoug]

You’ll need to find a steeper hill but it does moderate speed on gradients up to around -5%. Kinda runs away afterwards beeps but doesn’t try very hard to hold it back from creeping faster.

The approach to the eisenhower tunnel is a 6% grade.

 

[DigbyG]

Every time I go up and over a hill when in active cruise control, the car adds power to maintain speed up the hill but once on top, the acceleration continues briefly, pushing the speed up to 5 kph over the set speed, so the over speed warning beeps come on. 4 loud warning beeps on every hilltop. The control algorithm seems to be set too precisely but my dealer knows of no way to adjust or turn it down or off. Anyone else?

 

[RobertB]

I believe the control algorithm gain changes with driving mode. Economy- Mild , Normal - Normal , Power - Aggressive

 

[SmellyTofu]

It seems reading the manual carefully coz it mentions that it is not appropriate to use CC on downhills so that it appears it has changed from "Try as hard as you can to hold the speed" coz in my Prius v, even the engine can kick in for compression braking to keep the car at the set speed if/when required to "Try a bit but don't try too hard to hold the set speed" coz you can see the CC regen a bit but appears to give up if it goes beyond half way on the regen power meter.

@DigbyG I've looked into Techstream and there doesn't seem to be anything there the dealers can "tweak" to change any parameter on the CC.