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Isc Learning Procedure (without Lexus Diagnostic Tester)

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Lexus has a TSB regarding the ISC learning procedure. Supposedly the idle speed will be off if this is not done after the battery goes dead or is disconnected. Apparently, mileage may suffer if this is not done.

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Here's the TSB - EG010_05.pdf

The TSB says you need to hook the vehicle up to the Lexus diagnostic tester (which the dealer has and you don't) but I found a post here

http://www.greenhybrid.com/discuss/f31/400...ification-8126/

that shows it can be done without the tester. The tester is needed to make sure the vehicle is 181 degrees or higher, which you can do by driving it for a decent amount of time with the engine (so no stealth driving to your destination in electric only mode - drive it like you stole it so it heats up).

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The instructions are as follows -

This applies to the 2006 Highlander Hybrid also.

Note that you can probably perform the procedure yourself.

The scan tool mentioned in the procedure checks the coolant temperature to make sure it is at full operating temperature and checks the engine loading to make sure the load is sufficient to charge the battery and finally checks the status of the ISC learning parameter. It is not necessary to monitor these parameters if you do the procedure carefully.

1) Make sure the vehicle is fully warmed up. Do the procedure immediately following a long drive that runs the engine (highway speeds are best - not long gliding stealth runs at low speeds with the engine off). This will insure the coolant temp is at FULL operating temperature - it is not necessary to actually measure the coolant temperature if you warm up the engine sufficiently and don't let the engine shut down too long and cool off before doing the procedure.

2) With the vehicle stopped and in drive, press firmly on the brake to keep the vehicle from moving and then step on the accelerator while watching the power meter (to the left of the speedometer). Press down on the accelerator to keep the needle between 1/2 and 3/4 up the scale. You will find that the engine management system will automatically limit the engine load no matter how far you press down on the pedal so the amount you press is not critical as long as it is either 1/2 scale or to the engine's self-limiting load value. Keep the engine loaded for a full 30 seconds but not longer than 40 seconds (this procedure brings the hybrid battery up to a maximum state of charge - if you watch the battery symbol, you willl see it tick up to a "full" display).

3) Shut off the engine and place it in park

4) Wait 5 seconds.

5) Turn the ignition key back on to display "ready"

6) make sure the A/C and heater system controls are set to off

6) Lightly step on the accelerator pedal until the engine starts -then immediately take your foot off the accelerator and let the engine run until it stops by itself.

This completes the procedure.

_______________________________________

I've done this procedure successfully a few times now (ran my battery dead once, and disconnected another time when trying to reset the NAV system)

The only thing I noticed (and it didn't seem to matter) was that I could not get the power meter anywhere near 1/2 to 3/4. No matter how far I depressed the accelerator, the engine management system would not let the power climb even 1/4 way. Everthing else worked as stated though.

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Thank you SOOO much for this post and directions. I did the reset after my battery got low, and it is a new car entirely.

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How can you tell if this activity actually changed anything?

Is there a behavior difference or a reading somewhere to indicate the ISC is up to speed (or not)?

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Lexus has a TSB regarding the ISC learning procedure. Supposedly the idle speed will be off if this is not done after the battery goes dead or is disconnected. Apparently, mileage may suffer if this is not done.

___________________________________

Here's the TSB - EG010_05.pdf

The TSB says you need to hook the vehicle up to the Lexus diagnostic tester (which the dealer has and you don't) but I found a post here

http://www.greenhybrid.com/discuss/f31/400...ification-8126/

that shows it can be done without the tester. The tester is needed to make sure the vehicle is 181 degrees or higher, which you can do by driving it for a decent amount of time with the engine (so no stealth driving to your destination in electric only mode - drive it like you stole it so it heats up).

___________________________________

The instructions are as follows -

This applies to the 2006 Highlander Hybrid also.

Note that you can probably perform the procedure yourself.

The scan tool mentioned in the procedure checks the coolant temperature to make sure it is at full operating temperature and checks the engine loading to make sure the load is sufficient to charge the battery and finally checks the status of the ISC learning parameter. It is not necessary to monitor these parameters if you do the procedure carefully.

1) Make sure the vehicle is fully warmed up. Do the procedure immediately following a long drive that runs the engine (highway speeds are best - not long gliding stealth runs at low speeds with the engine off). This will insure the coolant temp is at FULL operating temperature - it is not necessary to actually measure the coolant temperature if you warm up the engine sufficiently and don't let the engine shut down too long and cool off before doing the procedure.

2) With the vehicle stopped and in drive, press firmly on the brake to keep the vehicle from moving and then step on the accelerator while watching the power meter (to the left of the speedometer). Press down on the accelerator to keep the needle between 1/2 and 3/4 up the scale. You will find that the engine management system will automatically limit the engine load no matter how far you press down on the pedal so the amount you press is not critical as long as it is either 1/2 scale or to the engine's self-limiting load value. Keep the engine loaded for a full 30 seconds but not longer than 40 seconds (this procedure brings the hybrid battery up to a maximum state of charge - if you watch the battery symbol, you willl see it tick up to a "full" display).

3) Shut off the engine and place it in park

4) Wait 5 seconds.

5) Turn the ignition key back on to display "ready"

6) make sure the A/C and heater system controls are set to off

6) Lightly step on the accelerator pedal until the engine starts -then immediately take your foot off the accelerator and let the engine run until it stops by itself.

This completes the procedure.

_______________________________________

I've done this procedure successfully a few times now (ran my battery dead once, and disconnected another time when trying to reset the NAV system)

The only thing I noticed (and it didn't seem to matter) was that I could not get the power meter anywhere near 1/2 to 3/4. No matter how far I depressed the accelerator, the engine management system would not let the power climb even 1/4 way. Everthing else worked as stated though.

Thanks...I did all of this..now what? Will I see anything,any changes? Rey

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Yes, you'll now be able to enter destinations in the NAV while driving, be able to shut off the traction control, voice commands will actually work, and bluetooth will work with any phone.

In reality, you may see an increase in mileage. But, if your ISC didn't need the reset, you may see no difference. Have you ever disconnected or replaced your battery?

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Yes, you'll now be able to enter destinations in the NAV while driving, be able to shut off the traction control, voice commands will actually work, and bluetooth will work with any phone.

In reality, you may see an increase in mileage. But, if your ISC didn't need the reset, you may see no difference. Have you ever disconnected or replaced your battery?

I personally haven't but it has been...and a couple of months ago Lexus put in a new battery...old 12V died.

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Well, I did it, I reset the ISC thingy using your fabulous step by step post.....and this tank I got MORE than two full MPGs better. I will have to see if this keeps up but so far I went from around 24.5 to this last tankful, 26.9. I was wondering why in the past two years my MPGs went down. I hope this wasn't a fluke and it continues. 26.9 is fabulous for me! Warmly, Rey

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I just bought a 2006 RX400h and I'm getting like 18 mpg, which from the sounds of it, is terrible. I have tried to do the ISC reset like 3 times and it hasn't worked yet. My engine still kicks on 3 secs after "starting" the veh...and that's with no heater or anything else on. I tried warming up the veh by driving like 10 miles (a combo of city and hwy) and maybe I'm not getting it warm enough but I can't get it to work. I was able to get the green battery thing on my NAV to show "full" ticks on the last try but it still didn't work. Any thoughts from anyone? Do I need to attempt to drive like 30 miles on the highway or something rediculous? The engine temp was at normal (halfway) point when I tried it each time. I'm at a loss and I HATE that I'm getting 18 mpg with a hybrid.

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P.S. I will take it to the dealer if I have too but it sounds pretty pricey to have them do it. Also, does anyone know what the warranty is on the hybrid system? I have a like 86,000 miles on this vehicle.

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I just bought a 2006 RX400h and I'm getting like 18 mpg, which from the sounds of it, is terrible. I have tried to do the ISC reset like 3 times and it hasn't worked yet. My engine still kicks on 3 secs after "starting" the veh...and that's with no heater or anything else on. I tried warming up the veh by driving like 10 miles (a combo of city and hwy) and maybe I'm not getting it warm enough but I can't get it to work. I was able to get the green battery thing on my NAV to show "full" ticks on the last try but it still didn't work. Any thoughts from anyone? Do I need to attempt to drive like 30 miles on the highway or something rediculous? The engine temp was at normal (halfway) point when I tried it each time. I'm at a loss and I HATE that I'm getting 18 mpg with a hybrid.

Oh yes, there is something not right! The lowest that I have EVER gotten in the five plus years that I have had my 06 is in the 23s. I highest I got (this is all on one tank) is 27.1. It dropped down to averaging 24 then I did the ISC and now I am (my fourth tank after doing the reset) is in the high 25s,low 26. There is definitely something not right with your 400h and your LEXUS dealer should know what to do or what the problem is and fix it.

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I just bought a 2006 RX400h and I'm getting like 18 mpg, which from the sounds of it, is terrible. I have tried to do the ISC reset like 3 times and it hasn't worked yet. My engine still kicks on 3 secs after "starting" the veh...and that's with no heater or anything else on. I tried warming up the veh by driving like 10 miles (a combo of city and hwy) and maybe I'm not getting it warm enough but I can't get it to work. I was able to get the green battery thing on my NAV to show "full" ticks on the last try but it still didn't work. Any thoughts from anyone? Do I need to attempt to drive like 30 miles on the highway or something rediculous? The engine temp was at normal (halfway) point when I tried it each time. I'm at a loss and I HATE that I'm getting 18 mpg with a hybrid.

Hmmm. All I can offer is suggestions. To start with, disconnect the battery (negative terminal) for about 15mins before you do the ISC reset. This way you know you're starting from scratch. Make sure the vehicle is warmed up before you do the ISC reset. Make sure the A/C is off. Follow the directions - they are straight forward -. Reset your mileage computer after doing the reset. Don't expect it to immediately show 27mpg. Initially it will be high as the average MPG is only averaging a small amount of driving. You don't need the battery gauge to show full ticks, or even green ticks for this to work. It just a side effect from mashing down the gas pedal while the brakes are applied. On a cold start the engine will kick in anyway as the catalytic converters need to be warmed up for emissions. What you shouldn't find after doing the ISC reset is the engine starting up at the slightest touch of the gas pedal as you drive.

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P.S. I will take it to the dealer if I have too but it sounds pretty pricey to have them do it. Also, does anyone know what the warranty is on the hybrid system? I have a like 86,000 miles on this vehicle.

I believe it's 100,000 miles outside of CA.

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tried this procedure yesterday, could never get the needle to move anywhere away from the bottom of the scale...maybe I am missing something..When you say the battery goes to full, does that mean all bars are green or does it actually say full....

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tried this procedure yesterday, could never get the needle to move anywhere away from the bottom of the scale...maybe I am missing something..When you say the battery goes to full, does that mean all bars are green or does it actually say full....

I couldn't get the needle to do that either but it worked.

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I took my RX 400h in for its 60K service...runs like a top...I am also getting my Yokohama Parada Spec X tires tomorrow...anyway, I took in the tsb about the ISC and the man that I usually ask for at LEXUS had not heard of it...I explained that I did the reset myself and that ever since my car has jumped back up to 2gMPG just like it used to be before my battery (12v) was changed last year. I take too good of records for me to not notice every little point change so 2 full MPGs is significant. He now has the bulletin and hopefull that little education will help others that will complain as well about the sudden drop in MPGs. Once again, thank you LEXUS forum! You guys are great. Rey Bustos in sunny L.A.

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I just bought a 2006 RX400h and I'm getting like 18 mpg, which from the sounds of it, is terrible. I have tried to do the ISC reset like 3 times and it hasn't worked yet. My engine still kicks on 3 secs after "starting" the veh...and that's with no heater or anything else on. I tried warming up the veh by driving like 10 miles (a combo of city and hwy) and maybe I'm not getting it warm enough but I can't get it to work. I was able to get the green battery thing on my NAV to show "full" ticks on the last try but it still didn't work. Any thoughts from anyone? Do I need to attempt to drive like 30 miles on the highway or something rediculous? The engine temp was at normal (halfway) point when I tried it each time. I'm at a loss and I HATE that I'm getting 18 mpg with a hybrid.

Did you end up taking your car in? I'm dealing with the same issue right now. I recently replaced my battery (battery was bad) hoping the ISC Reset would stick... but no luck.

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I just bought a 2006 RX400h and I'm getting like 18 mpg, which from the sounds of it, is terrible. I have tried to do the ISC reset like 3 times and it hasn't worked yet. My engine still kicks on 3 secs after "starting" the veh...and that's with no heater or anything else on. I tried warming up the veh by driving like 10 miles (a combo of city and hwy) and maybe I'm not getting it warm enough but I can't get it to work. I was able to get the green battery thing on my NAV to show "full" ticks on the last try but it still didn't work. Any thoughts from anyone? Do I need to attempt to drive like 30 miles on the highway or something rediculous? The engine temp was at normal (halfway) point when I tried it each time. I'm at a loss and I HATE that I'm getting 18 mpg with a hybrid.

Did you end up taking your car in? I'm dealing with the same issue right now. I recently replaced my battery (battery was bad) hoping the ISC Reset would stick... but no luck.

No, I took the car in for its 60k...I had to educate them about the ISC...I did the ISC reset myself as per the directions left on this forum and it DID work for me...I keep very detailed records of mileage and it is now back to what it was before Lexus replaced my 12v...it is up between 1.5-2 full MPGs like what I was used to...I'm at a round 26MPGs again...for a while I could not, no matter what get it out of the 24s on any full tank...no possible way and it seemed weird that it was so sudden after my battery was replaced...they didn't see the oddity in that...it's not their car....

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I understand that the dealerships have to service and be aware of all the nuances of every model they sell, but really, they should have a binder for each model with all the TSBs inside (or at least accessible on the computer) and the damn technicians should be required to read them and know them. Same as anyone else with a job has to keep on top of new and changing information. At minimum, they should peruse the TSBs for the specific vehicle they are servicing each time they service for anything more than an oil change.

I find the ISC reset a bit ornery at times if you're doing it by yourself. I've had to perform the procedure a few times in a row to get it to work sometimes.

Again my suggestions - disconnect the battery and let the vehicle sit for about 10 -15 mins (remember you will now have to reset your windows, sunroof and power hatch as well). Make sure the vehicle is warmed up (warm it up BEFORE disconnecting the battery). Follow the instructions - you likely will not get the power meter to move very much, but you will hear the engine running at a higher speed when you step on the gas. You can push the gas pedal right to the floor and you'll notice the computer won't let the engine rev too high. 30-40 seconds.

Following the restart you should see the arrow in the display going from engine to battery ONLY. If I don't see this arrow, I usually shut everything off and start over, as it doesn't seem to work for me unless I see the charge arrow. Your experience may vary - you may want to continue even if you don't see the arrow.

You will notice the engine running at a high idle. After a short time, you will notice the idle speed drop (the arrow may stop showing engine to battery as well). After the idle speed drops from fast to slow, the engine should shut off within a minute or sooner (two minutes is the max I would wait). If the engine doesn't stop running within this time (one time I let it run on and it didn't shut off even after ten minutes), I go for a short drive and then do the whole thing again, making sure I turn off the ignition and wait a few seconds before starting it again to do the procedure from the beginning.

You should have the A/C off during this whole procedure as well (I like to shut the lights off too, if they are on)

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pschmoker,

I also bought my rx400h used. I had terrible mileage for the first few months until I perfected coasting and more importantly, until I replaced the auxiliary battery. The original has a "magic eye" thingy on it that indicates battery damage. Mine was nice and blue so I thought it is fine, but then the car had to be jumpstarted (yes, it was very embarrassing) so I checked the battery and found that 2 cells were shorted. The "magic eye" was in a third cell and that very cell was ok, so it showed blue.

I do not know what the connection is, lemon, the op here is much more knowledable than me, but I suspect that some sensor running off the aux battery reports false data and that misleads the controller to fire up the combustion engine...

My advice would be to replace the aux battery if you can borrow one, do the learning procedure and see what happens.

Let us know!

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Thanks for this. I have no dealer in my area. I have to take this to Toyota and I do not depend on them much.

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Hello Dear Members,

I live in Jordan middle east, & after trying to re learning the ISC, I lost the current average of 21 MPG now what I can see on screen is 17 up to 19 MPG, please help me shall I try to disconnect the Battery cables for like 5 minutes so things will go back to what it was on before the learning process ??? ( the battery cable was disconnected in Feb 2011)thanx a lot in advance my dear friends.

Ahmad T.

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Well, I did it, I reset the ISC thingy using your fabulous step by step post.....and this tank I got MORE than two full MPGs better. I will have to see if this keeps up but so far I went from around 24.5 to this last tankful, 26.9. I was wondering why in the past two years my MPGs went down. I hope this wasn't a fluke and it continues. 26.9 is fabulous for me! Warmly, Rey

Wow ... I've been away for a bit. I'm going to give this a try. I though it was my imagination, but after Lexus changed out a steering ecu and aligned our 4 wheels (which for whatever reason, made them disconnect the battery) the mpg's have been a bit low. We'll see if this makes a difference.

No, I took the car in for its 60k...I had to educate them about the ISC...I did the ISC reset myself as per the directions left on this forum and it DID work for me...I keep very detailed records of mileage and it is now back to what it was before Lexus replaced my 12v...it is up between 1.5-2 full MPGs like what I was used to...I'm at a round 26MPGs again...for a while I could not, no matter what get it out of the 24s on any full tank...no possible way and it seemed weird that it was so sudden after my battery was replaced...they didn't see the oddity in that...it's not their car....

Call me wacky ... but isn't is pathetic, that Lexus knows less about our rides (in some instances) than the owners do? Same deal with the steering ecu we had replaced due to a tsb. They never called ... never even suggested it when we complained about our ride pulling to the right. When I think of the tread we wasted, and the gas we wasted, and that they won't even own up to how wrong that is ... well ... maybe I shouldn't let incompetence get to me.

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Do we know if this procedure is applicable to any models later than the 2006 year mentioned in the TSB? (because I know that's a query my dealership will raise if they haven't seen it before)

Mike

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