ISC resetting - Been to the circus and I seen the elephant; can't fool me no more
03-09-12, 03:47 PM
#16
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OK, read what it says folks.
The ISC reset "reinitializes the idle speed control". Doing this "allows the ICE to relearn its optimal idle speed during the initial engine warm-up cycle or charging the HV battery".
It then notes that not doing so may result in customer complaints of engine running too long, reduced mileage, or transmission gear clatter.
So we are resetting the idle speed to "optimal" during the first engine warm-up cycle after the battery is changed. If the idle is initially too low and not corrected, you may have HV charging problems, makes sense. If it is initially too high, you may see a small decrease in fuel economy. I can see the transmission clatter being a problem if the idle speed is significantly too high (noise as the transmission engages).
Now NONE of the things that Toyota mentions as reasons why you want to have the ISC done are going to lead to the drastic fuel economy changes that people claim they get after having an ISC reset done. We see claims of 20% and up fuel economy increases. No way an idle speed correction can do that. The engine idles only a very small portion of the time the car is driven and even then it is just sipping fuel. You get your real fuel consumption under acceleration or constant high speed and that has zip to do with idle speed settings. Read what Toyota says and then think about what the words mean. They are telling you what the procedure does. It is minor stuff.
Further, I'll bet you that what Toyota is telling the service department to do after a bad battery or battery replacement "happens" (reset the ISC) is something that the engine computer will do itself, over time, after battery service, but they want to avoid the customer experiencing the noted stmptoms while the engine control self-adjusts by having it done on the service computer at the time of service. That makes perfect sense.
This also explains why a major Lexus dealership service department can not know about this. Not doing it may result in a small short-term mileage decrease, but the car will self-adjust, probably quickly. If you had dealers not performing this and it leading to major fuel economy decreases, you can bet on it that customers would be coming back and that would lead to another TSB reminding service departments to not forget to do this. That would get their attention, I submit.
Designing the car so that after a battery change mileage goes to hell big time and the car cannot adjust to the new battery w/o being put on a service computer makes absolutely no sense and would be gross engineering incompetence. Not likely from Toyota.
- geo
The ISC reset "reinitializes the idle speed control". Doing this "allows the ICE to relearn its optimal idle speed during the initial engine warm-up cycle or charging the HV battery".
It then notes that not doing so may result in customer complaints of engine running too long, reduced mileage, or transmission gear clatter.
So we are resetting the idle speed to "optimal" during the first engine warm-up cycle after the battery is changed. If the idle is initially too low and not corrected, you may have HV charging problems, makes sense. If it is initially too high, you may see a small decrease in fuel economy. I can see the transmission clatter being a problem if the idle speed is significantly too high (noise as the transmission engages).
Now NONE of the things that Toyota mentions as reasons why you want to have the ISC done are going to lead to the drastic fuel economy changes that people claim they get after having an ISC reset done. We see claims of 20% and up fuel economy increases. No way an idle speed correction can do that. The engine idles only a very small portion of the time the car is driven and even then it is just sipping fuel. You get your real fuel consumption under acceleration or constant high speed and that has zip to do with idle speed settings. Read what Toyota says and then think about what the words mean. They are telling you what the procedure does. It is minor stuff.
Further, I'll bet you that what Toyota is telling the service department to do after a bad battery or battery replacement "happens" (reset the ISC) is something that the engine computer will do itself, over time, after battery service, but they want to avoid the customer experiencing the noted stmptoms while the engine control self-adjusts by having it done on the service computer at the time of service. That makes perfect sense.
This also explains why a major Lexus dealership service department can not know about this. Not doing it may result in a small short-term mileage decrease, but the car will self-adjust, probably quickly. If you had dealers not performing this and it leading to major fuel economy decreases, you can bet on it that customers would be coming back and that would lead to another TSB reminding service departments to not forget to do this. That would get their attention, I submit.
Designing the car so that after a battery change mileage goes to hell big time and the car cannot adjust to the new battery w/o being put on a service computer makes absolutely no sense and would be gross engineering incompetence. Not likely from Toyota.
- geo
I had my 12v battery replaced a month ago - car still drives exactly as before. No-one here has heard of a ISC rest either.
01-18-13, 08:20 AM
#17
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Brand new 2013 rx450h here. Does the TSB apply to the 2013 model?
I'm getting horrible gas mileage right now. Got 18MPG on previous 2 tanks and 21 halfway through this current one (using the pulse-coast technique). I am set to bring vehicle in for regular maintenance in 2 weeks, so I will question them then.
I'm getting horrible gas mileage right now. Got 18MPG on previous 2 tanks and 21 halfway through this current one (using the pulse-coast technique). I am set to bring vehicle in for regular maintenance in 2 weeks, so I will question them then.
01-18-13, 05:30 PM
#18
The procedure is well laid out in the service manual, and is important enough that Toyota saw fit to issue a TSB on the procedure as well - I would guess because a lot of technicians were not doing the reset as called for int he service manual.
01-18-13, 08:23 PM
#19
Interesting reading indeed, I wasn't aware of this ISC reset thing - let alone that it's required after any 12V battery disconnection.
By chance, is there any way to perform this reset without the TIS Techstream?
Anyway, here's my 2c of experience with the 12V battery on a 2008 400h:
1) managed to flatten it completely after leaving an internal light on for almost a week.
2) restarted the car with jumper cables, with no perceivable problem whatsoever.
3) aside from being more careful with lights
, since I often leave the car unused (sometimes for up to 3 months in a row), I asked the chief mechanic at my dealer if it would make sense to detach the negative of the 12V battery before leaving. The answer was yes, absolutely. He even told me that this is what they normally did when they had new cars arriving from the factory, but not meant to be delivered right away to a final client. No mention at all of the ISC reset need.
4) since then, I detached/re-attached the battery another three times, before/after leaving the car unused for some time. Never experienced any problems or differences in behaviour.
I guess what I'm saying is that the ISC reset can't be really critical.
It's probably just a matter of very fine tuning initially, and subsequently self-adjusted by the car anyway.
I accept that Toyota wouldn't have issued a bulletin with no reason at all, but I tend to agree with the OP that it would be lousy engineering if after detaching the 12V battery once, for whatever reason, without resetting the ISC afterwards, the car would continue to run badly forever.
And 20% or so mileage improvements due to this thing alone is pure nonsense anyway, even assuming that the car doesn't self-adjust the idle after a while.
By chance, is there any way to perform this reset without the TIS Techstream?
Anyway, here's my 2c of experience with the 12V battery on a 2008 400h:
1) managed to flatten it completely after leaving an internal light on for almost a week.
2) restarted the car with jumper cables, with no perceivable problem whatsoever.
3) aside from being more careful with lights
, since I often leave the car unused (sometimes for up to 3 months in a row), I asked the chief mechanic at my dealer if it would make sense to detach the negative of the 12V battery before leaving. The answer was yes, absolutely. He even told me that this is what they normally did when they had new cars arriving from the factory, but not meant to be delivered right away to a final client. No mention at all of the ISC reset need.4) since then, I detached/re-attached the battery another three times, before/after leaving the car unused for some time. Never experienced any problems or differences in behaviour.
I guess what I'm saying is that the ISC reset can't be really critical.
It's probably just a matter of very fine tuning initially, and subsequently self-adjusted by the car anyway.
I accept that Toyota wouldn't have issued a bulletin with no reason at all, but I tend to agree with the OP that it would be lousy engineering if after detaching the 12V battery once, for whatever reason, without resetting the ISC afterwards, the car would continue to run badly forever.
And 20% or so mileage improvements due to this thing alone is pure nonsense anyway, even assuming that the car doesn't self-adjust the idle after a while.
01-20-13, 10:28 AM
#20
Driver
Thread Starter
It's the cold weather
Don't worry about it. It's the cold weather. Hybrid mileage takes a brutal beating in cold weather. With our 2008 RX400h we drop about 20% in cold weather. My wife averages 25 mpg in warm weather and she is getting 20.0 mpg now (mid-Michigan). It's 23 F today.
We got our car in December 2011 and I thought that there was something very wrong with it as the mileage was nowhere near the EPA estimate until spring came...then it went way up.
All cars suffer w.r.t. mileage in cold weather, but hybrids, electrics, and diesels seem to suffer most, epecially with short commutes.
Wait for spring...you will be much happier.
- geo
We got our car in December 2011 and I thought that there was something very wrong with it as the mileage was nowhere near the EPA estimate until spring came...then it went way up.
All cars suffer w.r.t. mileage in cold weather, but hybrids, electrics, and diesels seem to suffer most, epecially with short commutes.
Wait for spring...you will be much happier.
- geo
Brand new 2013 rx450h here. Does the TSB apply to the 2013 model?
I'm getting horrible gas mileage right now. Got 18MPG on previous 2 tanks and 21 halfway through this current one (using the pulse-coast technique). I am set to bring vehicle in for regular maintenance in 2 weeks, so I will question them then.
I'm getting horrible gas mileage right now. Got 18MPG on previous 2 tanks and 21 halfway through this current one (using the pulse-coast technique). I am set to bring vehicle in for regular maintenance in 2 weeks, so I will question them then.
01-21-13, 06:33 AM
#21
Interesting reading indeed, I wasn't aware of this ISC reset thing - let alone that it's required after any 12V battery disconnection.
By chance, is there any way to perform this reset without the TIS Techstream?
Anyway, here's my 2c of experience with the 12V battery on a 2008 400h:
1) managed to flatten it completely after leaving an internal light on for almost a week.
2) restarted the car with jumper cables, with no perceivable problem whatsoever.
3) aside from being more careful with lights, since I often leave the car unused (sometimes for up to 3 months in a row), I asked the chief mechanic at my dealer if it would make sense to detach the negative of the 12V battery before leaving. The answer was yes, absolutely. He even told me that this is what they normally did when they had new cars arriving from the factory, but not meant to be delivered right away to a final client. No mention at all of the ISC reset need.
4) since then, I detached/re-attached the battery another three times, before/after leaving the car unused for some time. Never experienced any problems or differences in behaviour.
I guess what I'm saying is that the ISC reset can't be really critical.
It's probably just a matter of very fine tuning initially, and subsequently self-adjusted by the car anyway.
I accept that Toyota wouldn't have issued a bulletin with no reason at all, but I tend to agree with the OP that it would be lousy engineering if after detaching the 12V battery once, for whatever reason, without resetting the ISC afterwards, the car would continue to run badly forever.
And 20% or so mileage improvements due to this thing alone is pure nonsense anyway, even assuming that the car doesn't self-adjust the idle after a while.
By chance, is there any way to perform this reset without the TIS Techstream?
Anyway, here's my 2c of experience with the 12V battery on a 2008 400h:
1) managed to flatten it completely after leaving an internal light on for almost a week.
2) restarted the car with jumper cables, with no perceivable problem whatsoever.
3) aside from being more careful with lights
, since I often leave the car unused (sometimes for up to 3 months in a row), I asked the chief mechanic at my dealer if it would make sense to detach the negative of the 12V battery before leaving. The answer was yes, absolutely. He even told me that this is what they normally did when they had new cars arriving from the factory, but not meant to be delivered right away to a final client. No mention at all of the ISC reset need.4) since then, I detached/re-attached the battery another three times, before/after leaving the car unused for some time. Never experienced any problems or differences in behaviour.
I guess what I'm saying is that the ISC reset can't be really critical.
It's probably just a matter of very fine tuning initially, and subsequently self-adjusted by the car anyway.
I accept that Toyota wouldn't have issued a bulletin with no reason at all, but I tend to agree with the OP that it would be lousy engineering if after detaching the 12V battery once, for whatever reason, without resetting the ISC afterwards, the car would continue to run badly forever.
And 20% or so mileage improvements due to this thing alone is pure nonsense anyway, even assuming that the car doesn't self-adjust the idle after a while.
Toyota issued a TSB. They didn't do it for kicks and giggles.
The dealer knows nothing about an ISC reset...maybe this is why Toyota issued the TSB.
The procedure IS IN THE SERVICE MANUAL, even before the TSB came out. Maybe the dealer should do some required reading. Even easier than reading the service manual, have them look up the TSB.
The car does not 'self adjust' - this is why there is a procedure in the service manual to adjust the ISC. I have the service manual for the 400h. There is no mention of a self adjust, BUT there is, clearly laid out, the ISC reset procedure.
As for poor engineering on the part of Toyota - my MDX has a similar procedure to adjust the idle speed. My Maxima also. I have service manuals for both vehicles, and have read the procedure. Most never vehicles with electric throttles (i.e. no cable connection from gas pedal to throttle - it's all electric/electronic) will have some sort of procedure for idle speed.
Last edited by rcy; 01-21-13 at 06:44 AM.
01-21-13, 06:42 AM
#22
1MZ-FE sludge engine
Unintended acceleration / mat / gas pedal debacle
Water pump / steering shaft defect in the Prius
Inverters failing / subsequent recall on the 400h
Electric steering internal recall on the 400h
Oil line blow outs on the RX350
Tacoma defect front driveshafts
There's more...I just don't feel like listing them all.
I really don't have to go on, do I?
01-21-13, 01:07 PM
#23
Well, on the other hand I'm not amazed anymore by how people in forums try to manipulate other posters opinions, just for the sake of proving their own position.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
01-21-13, 02:45 PM
#24
Well, on the other hand I'm not amazed anymore by how people in forums try to manipulate other posters opinions, just for the sake of proving their own position.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
01-21-13, 02:53 PM
#25
Well, on the other hand I'm not amazed anymore by how people in forums try to manipulate other posters opinions, just for the sake of proving their own position.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
What's the point in highlighting bits and pieces of what I said, and then sentence that...
"Toyota issued a TSB. They didn't do it for kicks and giggles."
...when I also said:
"I accept that Toyota wouldn't have issued a bulletin with no reason at all" ?!?
I simply reported my experience, and that is it, whether you like it or not.
Otoh, I also asked if there's a way to perform the ISC reset without the TIS techstream, because even if I remain skeptic about its relevance, I'd rather do it for good measure.
Since you seem to have studied this in detail, maybe you can answer that?
And last but not least, if you have any sound technical justification of how a ISC tuning can bring a 20% mileage improvement, I'm all ears.
In fact, I could hardly think of engineering reasons why an ISC reset could affect the mileage by TWO percent - if that.
From the TSB:
Engine runs too long or more frequently than normal
Reduced fuel economy
Transmission gear “clatter” noise at idle is more pronounced
As for proving my position - there's nothing to prove. The official Toyota TSB and the service manual outline the ISC reset. It's entirely your choice to do it or not.
01-21-13, 04:54 PM
#27
Driver
Thread Starter
Oh please...
1. I have yet to read of anyone saying that their Lexus service department knew about this TSB let alone acted on it when a battery was changed. This is not to say that none have, just that no one has reported it. There are plenty of these things that have had the aux. battery replaced by now...they are pretty crappy batteries, after all. If this reset thing was a big deal and many or most dealers were not doing it (ignorant of it), then you can bet your boots you would have customers *****ing to their dealers about "What did you do to my car...the mileage went to hell after it was in your shop?" Or, they'd be whining to the dealer about crappy mileage after they changed the battery themselves. If it's happening, I have seen/heard nothing about it. has anyone else?
2. I am the OP and in my case we had a bad battery replaced under warranty. the battery had out of the car for testing at an auto parts store before we had it replaced by Lexus. No resetting of any sort was done after the battery was tested. the car was delivering the expected warm weather mileage, ~25 mpg city/highway (both) It had actually delivered near 30 mpg on a short steady speed in-city run, but that was unusual. After the battery was replaced, I called the service technicians attention to this TSB. They had not heard of it, but they did it, following the instructions on their screen. After the battery switch and reset the car's mileage was 25/25 city/highway (both). Reset this precisely nothing. Fact. Observed first hand by me...someone who would love to see a 20% improvement ot whatever the heck people are claiming.There ain't no Santy Caus, either.
3. As for the TSB, I still think that what Toyota has in mind is that after a aux. battery change it takes a while for the engine computer to re-learn a proper idle speed. There are plenty of cars now that supposedly learn your driving pattern and adjust engine/transmission operation to match the pattern. You can do al sorts of weird stuff with computer controls. I'm guessing (yeah, guessing) is that Toyota's reset trick is aimed as folks who are too impatient to let the computer re-learn and ***** right away (after battery change) about different operation. The reset might be a kludge to speed the process up. Just a guess, but the idea that a modern computer-controlled engine cannot re-learn something as basic as idle speed without being put on a service computer is just too mind boggling to even entertain from a company with a competent engineering department.
4. OK, we are in acircle now. Just for fun, I am going to call a few Lexus dealer service departments and play dumb as ask about thenecessity of this reset stuff after I changed the battery on my 6 year old RX400h. let you know what I learn. hell, I may even contact Lexus. Come to think of it, the Highlander has the same powertrain...maybe it's worth seeing what Toyota service has to say.
- nopcbs
2. I am the OP and in my case we had a bad battery replaced under warranty. the battery had out of the car for testing at an auto parts store before we had it replaced by Lexus. No resetting of any sort was done after the battery was tested. the car was delivering the expected warm weather mileage, ~25 mpg city/highway (both) It had actually delivered near 30 mpg on a short steady speed in-city run, but that was unusual. After the battery was replaced, I called the service technicians attention to this TSB. They had not heard of it, but they did it, following the instructions on their screen. After the battery switch and reset the car's mileage was 25/25 city/highway (both). Reset this precisely nothing. Fact. Observed first hand by me...someone who would love to see a 20% improvement ot whatever the heck people are claiming.There ain't no Santy Caus, either.
3. As for the TSB, I still think that what Toyota has in mind is that after a aux. battery change it takes a while for the engine computer to re-learn a proper idle speed. There are plenty of cars now that supposedly learn your driving pattern and adjust engine/transmission operation to match the pattern. You can do al sorts of weird stuff with computer controls. I'm guessing (yeah, guessing) is that Toyota's reset trick is aimed as folks who are too impatient to let the computer re-learn and ***** right away (after battery change) about different operation. The reset might be a kludge to speed the process up. Just a guess, but the idea that a modern computer-controlled engine cannot re-learn something as basic as idle speed without being put on a service computer is just too mind boggling to even entertain from a company with a competent engineering department.
4. OK, we are in acircle now. Just for fun, I am going to call a few Lexus dealer service departments and play dumb as ask about thenecessity of this reset stuff after I changed the battery on my 6 year old RX400h. let you know what I learn. hell, I may even contact Lexus. Come to think of it, the Highlander has the same powertrain...maybe it's worth seeing what Toyota service has to say.
- nopcbs
With the ISC reset done, the vehicle idles less and the ICE doesn't run as often when driving. Without the ISC reset, the ICE tends to run with the slightest press of the gas pedal and idle when it's not required. Less use of the ICE leads to less gas being consumed. Is that sound and technical enough - engine not running - no gas being used.
From the TSB:
Engine runs too long or more frequently than normal
Reduced fuel economy
Transmission gear “clatter” noise at idle is more pronounced
As for proving my position - there's nothing to prove. The official Toyota TSB and the service manual outline the ISC reset. It's entirely your choice to do it or not.
From the TSB:
Engine runs too long or more frequently than normal
Reduced fuel economy
Transmission gear “clatter” noise at idle is more pronounced
As for proving my position - there's nothing to prove. The official Toyota TSB and the service manual outline the ISC reset. It's entirely your choice to do it or not.
01-22-13, 12:52 AM
#28
With the ISC reset done, the vehicle idles less and the ICE doesn't run as often when driving.
Without the ISC reset, the ICE tends to run with the slightest press of the gas pedal and idle when it's not required.
Less use of the ICE leads to less gas being consumed.
Is that sound and technical enough - engine not running - no gas being used.
Without the ISC reset, the ICE tends to run with the slightest press of the gas pedal and idle when it's not required.
Less use of the ICE leads to less gas being consumed.
Is that sound and technical enough - engine not running - no gas being used.
The only thing your explanation shows is that it doesn't come from someone with a solid automotive engineering background.
A 20% mileage improvement out of reduced ICE usage implies that the ICE should run 20% less AT ANY GIVEN TIME - including (particularly!) when running at speed.
And the ISC reset (or lack of) should produce such result?
If this isn't a total nonsense, I don't know what else is.
01-22-13, 12:58 AM
#29
Just thought I'd point out that my MDX and my Maxima have a procedure for resetting / learning the idle speed. Seems like it might be something needed on a vehicle with an e throttle, perhaps. So despite Honda and Nissan being at least as competent as Toyota, their systems also require a special procedure to relearn the idle speed.
When my 400h was in getting a new inverter and then a new tranny, I asked the 'hybrid' technician about the ISC reset. He said he follows the procedure in the service manual step by step. So for something as complicated as inverter or tranny replacement where a technician might need the FSM due to the scope of the repair, the ISC would conceivably be done as it's one of the steps. I've seen this step in the FSM. However, I highly doubt a technician would use the FSM for a battery replacement or other simple repair where the battery needed to be disconnected, and the ISC reset would not be done. Maybe this is the reason Toyota saw it fit to release the TSB.
For what it's worth, I've spent many a time perusing the FSM and nowhere is it mentioned that the idle speed is self learning. However the ISC reset is mentioned in numerous procedures throughout the manual.
When my 400h was in getting a new inverter and then a new tranny, I asked the 'hybrid' technician about the ISC reset. He said he follows the procedure in the service manual step by step. So for something as complicated as inverter or tranny replacement where a technician might need the FSM due to the scope of the repair, the ISC would conceivably be done as it's one of the steps. I've seen this step in the FSM. However, I highly doubt a technician would use the FSM for a battery replacement or other simple repair where the battery needed to be disconnected, and the ISC reset would not be done. Maybe this is the reason Toyota saw it fit to release the TSB.
For what it's worth, I've spent many a time perusing the FSM and nowhere is it mentioned that the idle speed is self learning. However the ISC reset is mentioned in numerous procedures throughout the manual.
01-22-13, 01:12 AM
#30
It doesn't sound technical at all.
The only thing your explanation shows is that it doesn't come from someone with a solid automotive engineering background.
A 20% mileage improvement out of reduced ICE usage implies that the ICE should run 20% less AT ANY GIVEN TIME - including (particularly!) when running at speed.
And the ISC reset (or lack of) should produce such result?
If this isn't a total nonsense, I don't know what else is.
The only thing your explanation shows is that it doesn't come from someone with a solid automotive engineering background.
A 20% mileage improvement out of reduced ICE usage implies that the ICE should run 20% less AT ANY GIVEN TIME - including (particularly!) when running at speed.
And the ISC reset (or lack of) should produce such result?
If this isn't a total nonsense, I don't know what else is.
As stated in the TSB - engine runs too long or more frequently than normal. Not engine idles too much at stop. Also implying the engine will run more frequently at any given time.
Really, though, if you think you know the THS better than the engineers at Toyota that designed it, you can choose to ignore the TSB. Likely, it was just a make work project for the guy that works in the TSB creation department.
Last edited by rcy; 01-22-13 at 01:15 AM.
