Then what good was mandating that OBD-II store the codes even after a battery disconnect if they didn't also mandate that a generic scantool be able to see them?
'97 Camry - Way to Reset CEL without Scanner?
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Originally Posted By: MrCritical
Perhaps it depends on the scanner. The one the OEM's use will see codes after everything on the car is disconnected, including the PCM, unless you manually delete the code with the scanner.
Thats correct, the GM scanner is much higher tech than the off the shelf stuff.
Perhaps it depends on the scanner. The one the OEM's use will see codes after everything on the car is disconnected, including the PCM, unless you manually delete the code with the scanner.
Thats correct, the GM scanner is much higher tech than the off the shelf stuff.
Originally Posted By: brianl703
Then what good was mandating that OBD-II store the codes even after a battery disconnect if they didn't also mandate that a generic scantool be able to see them?
The maker of the scantool can decide what info they want to access, and charge you accordingly. I can only promise you that unless a code scanner shows you the code and clears it, the code is still there, no matter what else you do. And I don't sell scanners.
Then what good was mandating that OBD-II store the codes even after a battery disconnect if they didn't also mandate that a generic scantool be able to see them?
The maker of the scantool can decide what info they want to access, and charge you accordingly. I can only promise you that unless a code scanner shows you the code and clears it, the code is still there, no matter what else you do. And I don't sell scanners.
Someone made the claim that OBD-II is mandated to save codes even when the battery is disconnected.
If a scan tool that uses the legislated (aka generic) OBD-II protocols cannot access the stored codes after the battery is disconnected, then:
1)Either the OBD-II system is not complaint with what is mandated
or
2)There is no mandate that OBD-II system store codes after the battery is disconnected
or
3)The legislation did not specify that the codes must be stored in a manner accessible by legislated OBD-II protocols (that is, they did not specify how the codes that existed prior to battery disconnect are to be accessed).
Case #3 is moronic, and is an effectively unenforceable mandate (since independent verification that the system is working correctly requires access to proprietary automaker protocols).
I think case #2 is most likely.
As a side note, in all of the years I've been reading about OBD-II, I've read this bit about the battery disconnect not erasing codes and it was early enough on that I suspect the person who made that claim had not yet even worked on an OBD-II car (since they weren't out of warranty yet).
If a scan tool that uses the legislated (aka generic) OBD-II protocols cannot access the stored codes after the battery is disconnected, then:
1)Either the OBD-II system is not complaint with what is mandated
or
2)There is no mandate that OBD-II system store codes after the battery is disconnected
or
3)The legislation did not specify that the codes must be stored in a manner accessible by legislated OBD-II protocols (that is, they did not specify how the codes that existed prior to battery disconnect are to be accessed).
Case #3 is moronic, and is an effectively unenforceable mandate (since independent verification that the system is working correctly requires access to proprietary automaker protocols).
I think case #2 is most likely.
As a side note, in all of the years I've been reading about OBD-II, I've read this bit about the battery disconnect not erasing codes and it was early enough on that I suspect the person who made that claim had not yet even worked on an OBD-II car (since they weren't out of warranty yet).
Looks like this is only applicable to 2010 and newer cars. It's OBD-II mode $0A:
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A new OBDII mode will begin to show up on 2010 model year cars. A tenth mode, or what is officially known as Mode $0A, is required to be on 50% of cars made in 2010-2011. 100% on 2012 and later.
Essentially, Mode 10 is the "You cant fool us" mode. This mode is mainly for states with vehicle safety inspections.
As it is now, if you have a code stored in the ECU, it can be erased by clearing it with a scan tool, or disconnecting the battery for a short period of time. Mode 10 captures and stores this information and CANNOT be erased by either method. It will store the code(s) until the ECU determines the problem no longer exists. Which means it has to be fixed, and the ECU tests everything to make sure its good. No more "clear the code, hurry up and get it inspected before it comes back on" situations.
I could only find reference to it in CARB regulations dated 2005.
http://mustangforums.com/forum/general-tech/526921-new-obdii-mode-coming-in-2010-a.html
Anyhow, if they had to add this to the OBD-II specifications to apply to 2010 and newer vehicles...guess what..it doesn't apply to a 1997 Camry. So any capability that a 1997 Camry has to store codes through a battery disconnect isn't there because Toyota was mandated to do it. There was no such mandate back then.
As a side note, this really isn't doing anything as far as preventing people from cheating the test. If that's what they want, then all they need to do is require ALL of the monitors to be ready when the car is tested (that is, no P1000 code). They can do that with any OBD-II vehicle.
Quote:
A new OBDII mode will begin to show up on 2010 model year cars. A tenth mode, or what is officially known as Mode $0A, is required to be on 50% of cars made in 2010-2011. 100% on 2012 and later.
Essentially, Mode 10 is the "You cant fool us" mode. This mode is mainly for states with vehicle safety inspections.
As it is now, if you have a code stored in the ECU, it can be erased by clearing it with a scan tool, or disconnecting the battery for a short period of time. Mode 10 captures and stores this information and CANNOT be erased by either method. It will store the code(s) until the ECU determines the problem no longer exists. Which means it has to be fixed, and the ECU tests everything to make sure its good. No more "clear the code, hurry up and get it inspected before it comes back on" situations.
I could only find reference to it in CARB regulations dated 2005.
http://mustangforums.com/forum/general-tech/526921-new-obdii-mode-coming-in-2010-a.html
Anyhow, if they had to add this to the OBD-II specifications to apply to 2010 and newer vehicles...guess what..it doesn't apply to a 1997 Camry. So any capability that a 1997 Camry has to store codes through a battery disconnect isn't there because Toyota was mandated to do it. There was no such mandate back then.
As a side note, this really isn't doing anything as far as preventing people from cheating the test. If that's what they want, then all they need to do is require ALL of the monitors to be ready when the car is tested (that is, no P1000 code). They can do that with any OBD-II vehicle.
I've been working with OBD2 on a daily (5-6 day workweek) basis since it first appeared with GM on some 1994 Pontiac Bonnevilles (don't know about Caddy).
Disconnecting the battery will not clear codes. I see at least one every other day where someone has disconnected the battery and asks me to ck and see if the code has cleared.
The only thing anyone can possibly be referencing in regard to thinking that a power disconnect can clear codes would be if the "service engine soon" light came on, and no code was ever set in the first place. It happens.
Disconnecting the battery will not clear codes. I see at least one every other day where someone has disconnected the battery and asks me to ck and see if the code has cleared.
The only thing anyone can possibly be referencing in regard to thinking that a power disconnect can clear codes would be if the "service engine soon" light came on, and no code was ever set in the first place. It happens.
Originally Posted By: MrCritical
Disconnecting the battery will not clear codes.
Obviously that's not the case for all OBD-II vehicles. I can infer that from the fact that the OBD-II mandates were changed within the last 6 years to require "permanent failure codes" to be stored even when the battery has been disconnected.
Note: You are welcome to find the original OBD-II specification and cite the portion where it requires that the codes be stored even when the battery is disconnected.
Disconnecting the battery will not clear codes.
Obviously that's not the case for all OBD-II vehicles. I can infer that from the fact that the OBD-II mandates were changed within the last 6 years to require "permanent failure codes" to be stored even when the battery has been disconnected.
Note: You are welcome to find the original OBD-II specification and cite the portion where it requires that the codes be stored even when the battery is disconnected.
Originally Posted By: mikered30
Could it be possible that the ODB systems work differently on Toyotas vs other makes?
Yes. The OBD-II specifications which would apply to a 1997 that I've looked at do not specify that any codes are to be stored when the battery is disconnected. If they do not, then the manufacturer is free to make their own decision as to whether they want the codes to be stored in an area accessible only by the manufacturer's proprietary scantool.
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What is the difference between pulling the EFI relay vs disconnecting the battery when you want to clear a code? Or maybe it just clears select codes?
I don't think pulling the EFI relay will clear any codes. You will need to pull the EFI memory fuse, that is the fuse which supplies constant power to the computer. It may not be labeled as such.
Removing that memory fuse and disconnecting the battery will have identical results as far as the computer is concerned.
Could it be possible that the ODB systems work differently on Toyotas vs other makes?
Yes. The OBD-II specifications which would apply to a 1997 that I've looked at do not specify that any codes are to be stored when the battery is disconnected. If they do not, then the manufacturer is free to make their own decision as to whether they want the codes to be stored in an area accessible only by the manufacturer's proprietary scantool.
Quote:
What is the difference between pulling the EFI relay vs disconnecting the battery when you want to clear a code? Or maybe it just clears select codes?
I don't think pulling the EFI relay will clear any codes. You will need to pull the EFI memory fuse, that is the fuse which supplies constant power to the computer. It may not be labeled as such.
Removing that memory fuse and disconnecting the battery will have identical results as far as the computer is concerned.
before i bought a scanner i tried EVERYTHING to clear the CEL on my 01 grand prix. the ONLY 2 things that work on my car is A. fixing the problem, and B. clearing the code with a scanner.
i left the battery disconnected for a little over 2 days, and the CEL was still there right when i went to start it... (and the code was for the o2 sensor after the cat, so its not something that'd activate right when i started the engine)
i left the battery disconnected for a little over 2 days, and the CEL was still there right when i went to start it... (and the code was for the o2 sensor after the cat, so its not something that'd activate right when i started the engine)
Just a few days ago, a friend of mine with a '97 Camry had a CEL from a knock sensor.
I pulled the code with my scanner to diagnose.
I disconnected the battery, replaced knock sensors, re-connected the batter, and hooked up my scanner to clear the code, but there was NO CODE. So disconnecting the battery does clear the CEL on a '97 Camry.
I just used typical code reader/scanner.
Not a magical one that finds codes no one else can find.
I pulled the code with my scanner to diagnose.
I disconnected the battery, replaced knock sensors, re-connected the batter, and hooked up my scanner to clear the code, but there was NO CODE. So disconnecting the battery does clear the CEL on a '97 Camry.
I just used typical code reader/scanner.
Not a magical one that finds codes no one else can find.
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You have a cheap scanner that won't separate "current" and "history" codes.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
Originally Posted By: MrCritical
You have a cheap scanner that won't separate "current" and "history" codes.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
Do you listen to yourself? I cleared the current codes. And that's all that really matters.
If my engine blows up, and I rebuild it, do I still have a blown engine?
But you're one of those "I'm always right kind of people."
You have a cheap scanner that won't separate "current" and "history" codes.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
Do you listen to yourself? I cleared the current codes. And that's all that really matters.
If my engine blows up, and I rebuild it, do I still have a blown engine?
But you're one of those "I'm always right kind of people."
Originally Posted By: MrCritical
You have a cheap scanner that won't separate "current" and "history" codes.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
There is no OBD-II defined way to get history codes on a 1997 vehicle. The OBD-II specification that applies to a 1997 MY vehicle neither mandates that history codes be kept nor specifies how they are to be retrieved, and by extension, does not specify how they are to be cleared.
Any storage of history codes in that model year (and many that followed it, for that matter) is at the manufacturer's option.
As I recall, you first claimed on this thread that disconnecting the battery will not erase codes like clearing them with a scantool will...and this was a blanket statement applied to all OBD-II vehicles.
When given evidence to the contrary, you now claim that these codes continue to be stored despite a battery disconnect and it takes a special scantool to retrieve them.
Presumably, then, it takes a special scantool to clear those codes too(if the manufacturer supports "history codes"; as noted above there is no requirement that they do so), so, in the end, disconnecting the battery will have the same identical effect as clearing the codes with a low-end scantool.
In case you forgot:
Quote:
On OBD2 cars, disconnecting the battery does not erase memory.
You have a cheap scanner that won't separate "current" and "history" codes.
Once the code goes away from "current" on your low end scanner, it shows you that you don't have any codes.
You didn't "clear" anything.
There is no OBD-II defined way to get history codes on a 1997 vehicle. The OBD-II specification that applies to a 1997 MY vehicle neither mandates that history codes be kept nor specifies how they are to be retrieved, and by extension, does not specify how they are to be cleared.
Any storage of history codes in that model year (and many that followed it, for that matter) is at the manufacturer's option.
As I recall, you first claimed on this thread that disconnecting the battery will not erase codes like clearing them with a scantool will...and this was a blanket statement applied to all OBD-II vehicles.
When given evidence to the contrary, you now claim that these codes continue to be stored despite a battery disconnect and it takes a special scantool to retrieve them.
Presumably, then, it takes a special scantool to clear those codes too(if the manufacturer supports "history codes"; as noted above there is no requirement that they do so), so, in the end, disconnecting the battery will have the same identical effect as clearing the codes with a low-end scantool.
In case you forgot:
Quote:
On OBD2 cars, disconnecting the battery does not erase memory.
The BEST way, if you don't have a code reader, would be to go to AutoZone or other auto part store and have them do it with their code reader for FREE.
This will reset the current codes (I don't know about "stored" codes) and turn off the Check Engine Light WITHOUT clearing all your stored radio stations, etc.
It will take a little time for the OBDII "cycle" to complete before you are set to pass emmission testing as they connect and need to see that it is "ready".
So don't do this and head straight to the emmission testing station.
This will reset the current codes (I don't know about "stored" codes) and turn off the Check Engine Light WITHOUT clearing all your stored radio stations, etc.
It will take a little time for the OBDII "cycle" to complete before you are set to pass emmission testing as they connect and need to see that it is "ready".
So don't do this and head straight to the emmission testing station.
Some of the AutoZones will only read the codes, not reset them.
You can turn the code off but the computer will indicate the system is not ready and at least in NJ you will fail. They plug into the diagnostic port and read what's stored in the computer. Having completed all the test cycles is necessary to pass in NJ.
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