I am new to hybrids and I just got a 2006 400h. I know it is not the same technology as the Prius, but I was surprised that the 400h rarely runs in electric mode only. Turn the key and the gas motor comes on in a few seconds even before putting it in drive. At red light is the only time that the gas motor is off. Is this the way it is supposed to work?

 

Yes and no.
Does the ICE start a few seconds after you turn the key also when it's already warm?

In my '08 400h, it does start after a few seconds when it's cold, but after it warms up it only starts whenever:
a) the batteries are low, or
b) the speed is too high for electric alone (i.e. above 30 mph or so), or
c) you press the accelerator without thinking that there's an egg behind it.

Mind, even at low speed, you must indeed be EXTREMELY light on the accelerator, if you don't want to burn any gas...

 

It IS the same technology as the Prius, and all other Toyota/Lexus hybrids. The RX is a bigger, heavier vehicle, with a bigger combustion engine and a rear electric motor for AWD. Because of this, it will not run in electric-only mode as often as a Prius, but it will still do it under the same circumstances. You can get it in an extended "glide" if the engine is warm, and you are coasting or very light on the gas pedal on a level street, under 42 mph. It helps to have a ScanGauge II computer so you can see your engine RPM, temp, etc.

ScanGauge link: http://www.scangauge.com/

Source

 

Are you sure of this number?
I actually never checked that carefully, but I don't think to have ever seen it going in EV mode above (roughly) 30mph, as I previously mentioned...

 

Yes, but it will only do it when you are slowing down from a higher speed with the engine warmed up. I've done it many times with my 400h and I used to do it with a Prius. If you try to accelerate even slightly, the engine kicks in. The best you can do is hold 40 mph on a level or downhill road. There has to be a good charge on the battery too. On the other hand, when accelerating in EV mode, the combustion engine engages above 34 mph. In summary:

Acceleration: above 34 mph forces engine to run.
Decelerating/Coasting: below 42mph allows for "warp stealth" gliding in electric-only mode.

"Warp stealth" mode info:
Link 1
Link 2
Link 3

 

Interesting reading, many thanks.
Actually, I already realized, based on driving and engineering experience, that the driving style which they call pulse and glide gives a significant mileage improvement.
Though unfortunately, here in Europe, road conditions rarely allow its application.
Anyway, it's good to know also the exact speed limits at which the system works.
Just one question, the RX is never mentioned in your links, which are all related to the Prius.
How can you be sure that those numbers still stands also with the much heavier RX?

 

Update: today I had some time while I was driving around, so I thought to test my RX more carefully.
Indeed I've been able, with the battery well charged, to keep it going steady a tad above 40mph, on a level road.
Actually, I also managed to reach that speed from zero, without having the ICE kicking in, but only when accelerating veeeeeery slowly.
And even at higher speeds, after releasing the accelerator, I could keep the car going in the warp stealth mode above described, but with the speed constantly decreasing.
Maybe slowly, but surely decreasing. If I tried to accelerate just enough to keep the speed constant, from anything above 45mph, the ICE went on.
And such transition is extremely difficult to predict/control, it's really a matter of accelerating from say 28 to 29 (on a 0-100 scale)...!
While making these tests, I thought that it should be feasible to include in the ECU a functionality to exploit as much as possible the EV mode, to the limit where there's still no need to turn on the ICE.
Imho, it would make sense whenever the driver is not in a hurry and prefers to maximise the mileage. In fact, in some cases I found myself with the ICE kicking in just seconds before I would have released the accelerator, due to being approaching a red light or a slower car.
If I could have turned on such "economy" setting, the ECU should have avoided to turn on the ICE for nothing, and just for a few seconds.
Of course, it would have made sense to disable automatically such setting when pushing the accelerator hard, as in the kick off of traditional automatic transmissions.
I understand that the 450h can be "forced" in EV mode, but I'm not sure if that works as I'm envisaging... Does anyone know?

 

There is an EV mode status in the data bus of the RX. My ScanGauge shows it as OFF, but it's there, just like the Prius. I have the Coastal EV mode kit that I removed from my Prius before I sold it, but I haven't figured out how to install it in the RX yet.

http://www.coastaletech.com/electric_only_mode.htm

Everything about the hybrid system in the RX behaves the same as the Prius, so I think it may be possible to install the EV mode kit in the RX, if I can find the right wires to tap.

 

That sounds absolutely fantastic!
I suppose most hybrid owners are not aware (as myself) of the existance of this bit of kit, otherwise they would all rush to buy one! Well, I would, anyway.
Many thanks in advance for letting us know if you can find a way to make it work on the 400h!
Did you actually try it on your previous Prius, and does it work as explained in that webpage?
Also, what happens if/when the battery bank goes too low for EV?
I hope it's clever enough to turn automatically off the EV mode, rather than risking to drain the main batteries...?

 

Yeah I installed it on the Prius and it worked as advertised. When the battery state of charge gets too low, the engine kicks in as it normally would. It just takes advantage of the EV mode that is already programmed into the hybrid system, but there's no button for it on the North American models of Prius for those years.

I just haven't been able to find all the same wires on the RX schematics yet, to try it out.

 

Well, I for one would be very grateful if you could find it and enlighten us!

 

Well I hit a dead end with the EV button on the RX400h. The mod kit has only 3 wires, and I can find the cruise control switch and ground wires, but the important wire that goes to the hybrid vehicle control ECU is not listed on either the Prius or the RX schematics. On the Prius its connects to connector H14 pin 27, but it's not pinned so it's not listed on the schematic. If I could find where it goes on the Prius, maybe I could figure it out on the RX.

 

Aha, I see. Yeah, without any schematics reference it's really hard to guess.
Did you try asking those Coastal Electronic folks?
They must know pretty well the electric system of various cars, judging by their website...

 

Someone on this forum most certainly has access to RX400h wiring schematics.......can anyone chime in and help out MASEACE

 

I have the schematics, that's not the issue. I can't find the particular wire that is on the Prius schematic where the EV button kit connects. I need someone with knowledge beyond the schematics.