Clearing error codes: True or False
Thread Starter
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Clearing error codes: True or False
I want to clear my error codes on my stock '95 LT1. Will the following procedure work?
"To clear the codes from memory, remove the negative battery cable for a minimum of 10 seconds. Very Important: Make absolutely certain the ignition key is turned to the off position. You run the very real risk of destroying the ECM/PCM module if you connect the battery with the ignition switch turned on.
Disconnecting the battery will clear all stored codes but it will also clear the radio button presets, clock, trip odometer, average gas mileage memory, power seat memory (if you have that option) and anything else that stores something in memory. Your ECM/PCM computer will also have to relearn your driving habits again and adjust the timing/mixture/exhaust emissions to your driving style."
"To clear the codes from memory, remove the negative battery cable for a minimum of 10 seconds. Very Important: Make absolutely certain the ignition key is turned to the off position. You run the very real risk of destroying the ECM/PCM module if you connect the battery with the ignition switch turned on.
Disconnecting the battery will clear all stored codes but it will also clear the radio button presets, clock, trip odometer, average gas mileage memory, power seat memory (if you have that option) and anything else that stores something in memory. Your ECM/PCM computer will also have to relearn your driving habits again and adjust the timing/mixture/exhaust emissions to your driving style."
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Originally Posted by smacko
True AND false - ECM usually retains memory unless ASDL pins are jumped.
Service manual says disconnect power for 30 sec. That's it.
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Drifting
Joined: May 2003
Posts: 1,647
Likes: 28
From: Woodbridge NJ
Sounds right. I just cleared the codes this morning after replacing the timing chain. Codes 22 and 42. I disconnected the power for 10 seconds, reconnected and drove the car for about 20 minutes.
Thread Starter
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Thank you gentlemen! Since I still have not gotten a munual for my C4, could you please tell me where the ECM fuse is located? This sounds easier than disconnecting the neg. battery terminal, especially 'cuz previous owner stripped it, and I need to use vice-grips....DOH!
Burning Brakes
Joined: Feb 2004
Posts: 1,024
Likes: 0
From: Long Island New York
Originally Posted by MikeC4
Thank you gentlemen! Since I still have not gotten a munual for my C4, could you please tell me where the ECM fuse is located? This sounds easier than disconnecting the neg. battery terminal, especially 'cuz previous owner stripped it, and I need to use vice-grips....DOH!
I believe the fuse should be labelled ECM or ECMB possibly both. Should be in the main fuse panel; anyone confirm?
8th Gear
Joined: Jan 2005
Posts: 8
Likes: 0
ecm
Disconnect the battery, it is the easy way. You will loose your radio presets.
You did not want them anymore, right?
Key off it's the safest way, why would you leave it on anyway?
Recomend that till you get a book and be sure of what you want to do.
This is the sure way to make you car forget his "problems".
You did not want them anymore, right?
Key off it's the safest way, why would you leave it on anyway?
Recomend that till you get a book and be sure of what you want to do.
This is the sure way to make you car forget his "problems".
Thread Starter
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by bogus
Does this make sense:
1)codes thrown:
H-22
H-44
H-64
2)Then removed neg. bat cable for at least 30seconds or so:
3)Then reconnected neg. bat cable
4)Did not start engine
5)Checked to make sure codes cleared, but still got this:
H-64
(Right oxygen sensor voltage was below 0.2 volts for 50 seconds of closed loop operation.)
Shouldn't this code have cleared? Closed operation is with engine fully warmed up, and I didn't even fire it up?
Thanks in advance!!
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Originally Posted by MikeC4
5)Checked to make sure codes cleared, but still got this:
H-64 (Right oxygen sensor voltage was below 0.2 volts for 50 seconds of closed loop operation.)
Shouldn't this code have cleared? Closed operation is with engine fully warmed up, and I didn't even fire it up?
H-64 (Right oxygen sensor voltage was below 0.2 volts for 50 seconds of closed loop operation.)
Shouldn't this code have cleared? Closed operation is with engine fully warmed up, and I didn't even fire it up?
It says that this error can occur with the engine off, because the voltage should still be around 0.450 if the engine is off.
It does imply that the key would need to be on for 50 sec before the code would be set, so I'd expect it to be cleared right after the battery disconnect.
