Mileage depends on a lot of things. It is tough to say in any specific case because different driving techniques can result in significantly different results.

No, your battery should not be showing green most of the time. I think I've seen it green three times in a year.

 

And the confusion continues...... I purchased a set of RX400h manuals off of ebay, got a good deal on them but are for a 2007 model year...... and..... it has the procedure for resetting the ISC when the auxilliary battery is replaced/disconnected.... LOL!!!!!!!

 

if you have a 2006, how do you even know the ISC reset "worked"? without the Toyota computer, of course.

 

From what I have seen, if during the last step, you let the engine start up, it will vary RPM, then idle and shut off.... I saw another post and the guy said when he did the process wrong, the engine would start when you tapped the gas on the last step and would run for more than 30-40 seconds before shutting off automatically.

 

OK, unless I am missing something, what you did was that you did the ISC reset procedure on a 2008 RX400H that had NOT had the battery disconnected or fail. Then you disconnected the battery and reconnected it and then performed the same ISC reset procedure with the same behaviour by the car as the first time. I assume learning staus INCOMPL means that the testers ISC reset program has not run and COMPLETE just means that it has run.

I don't see that the test showed anything other than that you can run the ISC reset program on a 2008. I don't see that this shows that the ISC reset did or did not do anything.

What would be extremely interesting for someone like you with access to the tester is to establish mileage over a set course. Pull the battery for 10 minutes. Reconnect and then run the course agin and measure mileage. Finally do the ISC reset with the tester and run the course and measure mileage again. I'm guessing all three mileages would be the samw within experimental error. If the 1st and 3rd were much higher than the 2nd, that would be VERY instructive.

I personally have seen no benefit to a dealer doing an ISC reset after our 12V battery (2008 RX400h) reset. None at all. Also saw no change when first battery was failing and we had to jumop start car 3X w/o ISC resets.

- grl

 

ISC reset TSB applies to all years 2006 -2008.

See here - https://www.clublexus.com/forums/hyb...all-years.html

If you think you know your vehicle, and hybrid technology better than Toyota/Lexus, you can disregard the TSB and ISC reset. It's a free world (mostly) anyway.

 

Thanks for the share!

I bought this car recently in pristine condition with 95K and everything done at Lexus.

It was getting 23-27 which is very low considering i drive extremely efficiently. and it was 60%city

I did the RESET today after a 20min drive in 80 degree weather in socal. No hard drive or accelerating needed.

Did the reset and have driven 20 miles since in City/coastal highway

getting low to high 30's depending on driving area. Seems like average is around 33-35mpg which is what i was expecting in relation to EPA and my driving.

Excited but time will tell, although it seems good the gas meter hasn't even moved.


Battery seems old and I should check if it's been replaced but I was thinking of the Optima Yellow top..afraid it might some how lower my gas though


ALSO...the energy meter during the reset jumped up 1/4 the way for a split sec then it didnt even budget much. Though like others stated, it still worked.

I have a feeling people with newer and non defective batteries see the energy acceleration as opposed to us.




Thanks again and I'll share back what I learn

 

I too live in California and find your mileages way out on the positive side. The EPA only rated these guys for 25 to 27 miles per gallon and the best I have ever achieved was 25.5 with California gas. That being said the mpg as measured on the car is toward the high side by about 1.2 mpg when compared to using the old fashion way of dividing miles by gallons filled. Remember our gas in California is not friendly to mpg....

 

I am not sure of what you are saying about the 12v battery, but if you are saying its condition will affect gas mileage, I believe that is not so. The only possibility I can think of would be if older battery being slightly less efficient during charging would require slightly more energy to charge, the energy of course coming from fuel consumed.This difference in energy to charge a new vs an "old" battery would be infinitesimal compared to the energy used to propel the vehicle, heat, draft and friction losses. You would not see it measurably affect mileage.

 

It seems to be more consistently 27-32 right now.

the 36mpg to be fair, was on coastal inner highways where I was drive very slowly without having to stop or accelerate much at all. Most circumstanes wont be like that but good to know it's capable.

I don't doubt it because i can get 21-23 city in my ls460. Manually calculated

 

I believe the argument here does not relate to the 12v battery charge helping the mpg. but the computer that calculates the best fuel/air ratio etc for given conditions to get the best mpg When the battery gets disconnected or lower than the 7v the computer gets a bit wonky and loses its learned algorithms. and has to "relearn" the algorithm. Doing the ISC reset procedure tells the car computer to retrain it self.

I hope you guys are not basing your mileage solely on the screen. It is very i accurate. Use the miles driven/gas use for more accuracy as i reported here https://www.clublexus.com/forums/hyb...-accuracy.html

Don't base it on short drives. either. Data is best when given more samples.

 

Ok bringing this thread back from the dead. I have a 2006 rx400h and I can absolutely confirm that the ISC resets itself. Let me explain:

So last month I was bleeding the brakes using the Techstream software. All went well except towards the end where my 12v battery went dead. I jump start it and noticed that the ICE stayed ON way longer than usual. I connect the Techstream software and noticed that the ISC status was INCOMPL, even when the ICE shut off.

So, I disconnect the 12v battery and place a charger on it. The battery was disconnected for at least 3 hours. After the battery was fully charged I place it back in and initialized the windows, moon roof, etc. I start the vehicle with the Techstream still plugged in and guess what....the ISC display goes from INCOMPL to COMPLETE, as soon as the ICE shut off, which BTW went back to it's normal cycle duration just like the TSB said it would. I did not initiated the ISC reset procedure before this. My MPG never deviated from the norm which is around 21-22 MPG. For good measure I did perform the reset procedure but I believe it wasn't necessary.

I followed the TSB step by step and it clearly states that the ISC procedure is ONLY necessary if the Techstream software shows INCOMPL. The only theories I can come up with is that the previous owner had the dealership update the vehicles firmware or the Techstream software somehow assists in the procedure while plugged in, BTW I have version 10.10.018 if that matters. Other than that I can't figure it out.

 

I performed the isc reset following instructions from a different website. Now its doing everything opposite of what it was suppose to fix lol.

 

Did you do the isc reset like this?
try an ISC reset procedure to reset the battery charging logic.
When you reset the ISC, you idle around and drain the battery until the engine comes on, then shut the car down. You turn off all accessories and climate control (nothing electronic should be on). Put the car in run mode (start it), press the brake pedal, put the car in drive, then while holding the brake pedal down, press the accelerator pedal down.
The car will not move or rev much, but the engine will be on and start charging. Keep the gas pedal down for 40 seconds, then release it for a few moments, then down again for 40 seconds and keep doing that 40 on/10 off etc until the battery is fully charged (all green) and the engine no longer charges or revs slightly when you press the gas pedal down. Of course you're holding the brake pedal down all the time while doing this.
Shut down, put your accessories back where you want them, then you can start up and go anytime. Learn about pulse driving to maximize your mileage going forward

 

Hello thread,

I followed the instructions from the PDF for the ISC reset, but the engine load won’t go over 23% even after depressing the accelerator pedal all the way. As per the instructions, the engine load should be over 45% in order to do the ISC reset. My engine is barely turning off and I’m getting around 14 city and 20 highway.

Anyone know what’s going on?