flash14

My RX400h was manufactured 10/08, today, after a 15 minute drive, I hooked up the Lexus tester (Vetronix Mastertech 3100) as described in Lexus TSIB EG010-05, and followed the described ISC learning procedure.... The car was already warmed up and fully charged, so I turned the ignition to on, the ISC learning status showed "INCOMPL" on the Lexus Tester, as the instructions said it would, then turned the ignition to run, while the "INCOMPL" was being displayed, let the car start on its own, cycle off and when it did.... the display changed from INCOMPL to COMPLETE, just like the instruction in the SB said it would if it was done correctly..... Now for the test..... I disconnected the 12 volt engine compartment battery for 10 minutes, when I reconnected it and got inside, I turned the ignition to on and had to reset each window manually, the moonroof and rear door, and clock...... so once again turned on the Lexus tester and scrolled to the ISC Learning status page and when it came up, it showed as INCOMPL..... so I turned the ignition to run, after a few seconds, the engine started on its own,ran for about 2 minutes, then shut off, when the engine shut off, the status changed from INCOMPL to...... COMPLETE.... Drove the RX400 the same route and the MPG was nearly identical to before the battery was disconnected....

aucht

Only the 2006 model need to reset ISC.

rcy

The TSB was issued in 2006. We've never had a definitive answer as to whether the TSB applied to newer models. Based on the experience flash14 had, I would suggest that the ISC reset does need to be done.

flash14

Thanks rcy!!! That is exactly why I did it, after reading the countless threads online, now we know that the 2008 does it automatically

aucht

The ISC Reset TSIB already say "Applicable Vehicles: 2006 model year RX 400h vehicles".

flash14

The TSIB clearly states 2006...... you are correct, but........ alot of owners are claiming that they performed the reset on later model years with success/increased fuel economy...????
I wanted to see what the results would be and confirmed that the 2008 model is exempt from this procedure...... just like the TSIB states.... I thought it would be correct to inform my fellow RX400h owners....

aucht

How do they performed the reset when there is <<automaticly>> reset?????

rx400h1976

I always wondered about this one. So, thanks for testing it out and sharing the results.

flash14

You can go thru the reset procedure, the vehicle responds as if it is doing the reset, the second part with the ac off, you let the vehicle start, and cycle off.... the Lexus tester shows ICS Learning "Incomplete" until the engine shuts off, then the message changes to "Complete. If you disconnect the battery, you can tell that you have to normalize everything because the windows will only move from each door until the initialization is complete, same with rear door and moon roof.... hooked the Lexus tester up and the ICS learning came on as "Incomplete" I just sat in the car with the ac off, a few seconds later the engine started, like it usually does, rpm varied and then shut off, when it shut off, the ICS Learning changed to "Complete" I did nothing but have the key turned to on..... I actually did this twice with the same results..... Then I changed the personal settings to stop the steering wheel from retracting and set the moon roof to not open if you hold the remote's unlock button..... I did not like that on my RX300 either.....

aucht

The initialization and ISC reset is two different matter, once you connect the battery back on the initialization must need to be done. you don't have to do "vehicle start, and cycle off etc....." it will reset to "complete" after your first road trip that call automatically reset.

flash14

aucht you are correct, they are 2 different things, BUT....

TSIB REVISION NOTICE:

February 27, 2006: Step 3 of the ISC Learning Procedure and steps 3 and 7 of the
ISC Initialization Procedure have been updated.
Previous versions of this TSIB should be discarded.
When the 12–volt battery is disconnected or is depleted below 7 volts on 2006 model
year RX 400h vehicles, it is necessary to perform the ISC Learning procedure to
re–initialize the idle speed control. The information in this TSIB relates to this procedure.

flash14

AND yes, I understand that it ONLY applies to a 2006.......

flash14

aucht, if you look closely at the thread title, it states "ISC Reset TEST on a 2008 RX400h"

I understand that you know that it is NOT required on a 2008, but alot of owners are unsure, and claimed they had performed a ISC Reset with successful results..... This thread was initiated to show all RX400h owners what I had found on my own vehicle....

2xNewbie

I hate to add to anyone's frustrations, but maybe this will help . . .

I am one of the owners who went through the ISC reset for a 2008 400h. There are other posts that swear it applies to 2008 year, and as a Newbie, I did it only after owning my CPO for couple of weeks (bought end of July 2011). The mpg skyrocketed afterwards, but for 5-10 min ONLY! It went from 24 to over 40 mpg (terrain helped a bit). But I think something else is going on . . .

I drive the car mostly short runs, and the battery never shows more than 6 of the 8 bars. After I 'warmed it up' for the ISC procedure, I got a green battery light and 7 bars, first time since I bought it. It then ran like a charm, until it went back to the 6 bars (obviously moving up and down, but never more than the 6) and its regular mpg's, 24-25 city, 28 highway.

Should my battery be showing 'green' most of the time? (The car went on the road 3/09, sat on dealer lot for 2 months, I bought it end 7/11.) Has anyone noticed improved CITY mpg with new battery? My mpg's seem backward, should be higher in city, right?!

jtaylor3

Mine only goes green if I go down a long steep hill and the battery is mostly charged. I've never seen all bars, but I do see my battery green a few times a week.

Jeff
08 RX400h