Resetting the ECM. How?
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Joined: Mar 2001
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From: PA
Resetting the ECM. How?
I always thought that just disconnecting the battery would reset the ECM. While I was visiting LS1.com, I saw in a tech section that you have top remove 2 fuses to actually reset the ECM. The directions are as follows:
1. Turn key on but don't start car
2. Pull PCM BAT and PCM IGN fuses
3. Wait a few second
4. Turn ignition off
5. Replace fuses
Is this the proper way to do it? It also goes on to say that stored SES light codes can actually retard timing and spark ignition which of course will hinder performance. The reason I'm asking is that I'd like to reset my ECM just to make sure there are no codes stored that may in fact be negatively affecting my cars performance. Thanks!
Nat
[Modified by QuickSilver97, 7:49 AM 2/13/2002]
1. Turn key on but don't start car
2. Pull PCM BAT and PCM IGN fuses
3. Wait a few second
4. Turn ignition off
5. Replace fuses
Is this the proper way to do it? It also goes on to say that stored SES light codes can actually retard timing and spark ignition which of course will hinder performance. The reason I'm asking is that I'd like to reset my ECM just to make sure there are no codes stored that may in fact be negatively affecting my cars performance. Thanks!
Nat
[Modified by QuickSilver97, 7:49 AM 2/13/2002]
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Re: Resetting the ECM. How? (QuickSilver97)
I think the reason those instructions exist is so that you can reset the PCM without suffering the OTHER consequences of unhooking the battery such as lost radio pre-sets, lost seat/mirror position memory, lost keyless entry programming, etc.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
Melting Slicks
Joined: Jan 2001
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From: Chesapeake VA
Re: Resetting the ECM. How? (MattG)
I think the reason those instructions exist is so that you can reset the PCM without suffering the OTHER consequences of unhooking the battery such as lost radio pre-sets, lost seat/mirror position memory, lost keyless entry programming, etc.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
Thread Starter
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Joined: Mar 2001
Posts: 14,480
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From: PA
Re: Resetting the ECM. How? (Square)
I think the reason those instructions exist is so that you can reset the PCM without suffering the OTHER consequences of unhooking the battery such as lost radio pre-sets, lost seat/mirror position memory, lost keyless entry programming, etc.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
Please post your offical recommendations for a proper idle relearn.
I have always just unhooked the battery for 5 mins, then hooked it back up. Make sure to do an idle releard right away when you start the car after hooking it back up.
Please post your offical recommendations for a proper idle relearn.
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Re: Resetting the ECM. How? (QuickSilver97)
I am not sure of the exact instructions for an idle relearn on an A4, but I do know what I do for my M6.
I start the car and let it warm up to about 160 degrees. I then let it idle for 5 minutes with the air conditioning off, and then let it idle for 5 mins with the air conditioning on.
When you reset the PCM, your car has to relearn in order to make your car idle smooth in different driving conditions, such as a/c on, and a/c off, etc.
In an A4, it is fairly similar but you have to put the car in gear for a few minutes with your foot on the brake and let it idle I believe.
If you do not do an idle relearn, the car will eventually learn the idle from normal driving, but if you do the relearn, your idle will be smooth right away. The more modified your car is, the more important the idle relearn is.
I am sure someone on here has links to exact instructions for the idle relearn on an A4.
I start the car and let it warm up to about 160 degrees. I then let it idle for 5 minutes with the air conditioning off, and then let it idle for 5 mins with the air conditioning on.
When you reset the PCM, your car has to relearn in order to make your car idle smooth in different driving conditions, such as a/c on, and a/c off, etc.
In an A4, it is fairly similar but you have to put the car in gear for a few minutes with your foot on the brake and let it idle I believe.
If you do not do an idle relearn, the car will eventually learn the idle from normal driving, but if you do the relearn, your idle will be smooth right away. The more modified your car is, the more important the idle relearn is.
I am sure someone on here has links to exact instructions for the idle relearn on an A4.
Instructor
Joined: Aug 2000
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Re: Resetting the ECM. How? (MattG)
Matt:
Acyually that way is backwards. The service manual states to set the idle with the AC on for 5 min than let it idle with the AC off for 5 min and than shut car off for 30 seconds, :D
Acyually that way is backwards. The service manual states to set the idle with the AC on for 5 min than let it idle with the AC off for 5 min and than shut car off for 30 seconds, :D
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Re: Resetting the ECM. How? (98ISGR8)
See I told you I wasnt too sure of the exact directions :)
I don't think on an M6 it really matters though. The PCM is always learning the idle in different operating conditions and eventually it smoothes itself out. The relearn procedure just makes sure this learning process is done in 10 mins.
I don't think on an M6 it really matters though. The PCM is always learning the idle in different operating conditions and eventually it smoothes itself out. The relearn procedure just makes sure this learning process is done in 10 mins.
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