Resetting a chevy computer?

[LastDetail]

Hey everybody!
I just changed out my battery and now the car is idling extremely rough. I was wondering if anyone knows how to reset the computer on an '01 Chevy Tahoe? From what a friend told me it is idling rough because of the battery change. Any help would be appreciated.

[Jngrbrdman]

Typically just removing the ground on the battery for about 30 minutes will reset a computer. If that doesn't work then pull the ECU fuse and that will basically do the same thing. It should run rough for a little bit while the ECU relearns what the engine is doing, but then it smooths out. I'd give it a couple days before you reset it again.

[belcherm58]

When you disconnect the baterry for a few minutes it shoulld clear the computer. As far as trouble codes go. You could go to Autozone or Advance Auto and they can clear the trouble codes. I have never heard of problems that you describe from changing batteries. I know that on trouble codes that the computer can go into a failsafe mode if a sensor goes into a trouble code.
Some computers are supposed to learn some driving parameters, that should clear without electric supply.

[LastDetail]

Allright the negative is cable is off the battery and Im gonna let it chill for a little while before re-attaching.
Apparently the problem was after we swapped in the new battery it reset the computer, but nobody told me that I needed to drive it mild for a little while so the computer could re-learn whatever it needs to learn, so I just got on the freeway and pounded the pedal down and drove all the way home, (about an hour and a half) at 70-85 mph. Then when I got off the freeway the idle was horrible.
Hopefully this fixes it, I was thinking that it was the fuel pump.
Thanks for the quick responses guys.

[Sparkie]

Remove the negative (black) cable, and cut on the lights for at least 30 min.
Before anybody ask, cutting the lights on will take out any power in the system out.

[belcherm58]

Originally Posted by Sparkie

Remove the negative (black) cable, and cut on the lights for at least 30 min.
Before anybody ask, cutting the lights on will take out any power in the system out.

I could only see this if there is a capacitor in line. Some people with large
sound systems have these inline to handle system draws on peaks. Newer
cars do not use these and should not be affected. If you have them it might
be prudent to discharge or disconnect them for a reboot of the computer.
Be carefull about compacitors if you are unfamilar. They can be dangerous.
I learned this the hard way back when points were the norm. Touch it and
ouch, Where in the he double fiddle sticks did that come from.

[LastDetail]

Originally Posted by belcherm58

I could only see this if there is a capacitor in line. Some people with large
sound systems have these inline to handle system draws on peaks. Newer
cars do not use these and should not be affected. If you have them it might
be prudent to discharge or disconnect them for a reboot of the computer.
Be carefull about compacitors if you are unfamilar. They can be dangerous.
I learned this the hard way back when points were the norm. Touch it and
ouch, Where in the he double fiddle sticks did that come from.

Oh man! I completely forgot about the Cap! I do have a 1 farad capacitor for my system and it is still connected in line. Maybe this is why the reset didn't work the first time! Thank you so much.

[belcherm58]

Originally Posted by LastDetail

Oh man! I completely forgot about the Cap! I do have a 1 farad capacitor for my system and it is still connected in line. Maybe this is why the reset didn't work the first time! Thank you so much.

Be carefull. You can eiather ground it out with the battery disconnected to the frame or disconnect the wires, both sides. I can't say this enough. You would not beleive what they can hold as far as current is concerned.

[LastDetail]

All I had to do is pull the fuses for the amps, they are before the cap in line. So fuses out now the system is %100 disconnected. Thanks for caring about my well being though!

[belcherm58]

Originally Posted by LastDetail

All I had to do is pull the fuses for the amps, they are before the cap in line. So fuses out now the system is %100 disconnected. Thanks for caring about my well being though!

That is from the up side. Disconnect one wire from the down side. Different people wire these in different. I did a lot of upscale sound installations at one time.

[Dans Detailing]

Also the ECM must relearn and it does that VERY slowly if you let it idel, it needs to be drievn about 30-50 miles before is has enought long term fuel trim saved

[GearHead_1]

Originally Posted by DKKNE

Also the ECM must relearn and it does that VERY slowly if you let it idel, it needs to be drievn about 30-50 miles before is has enought long term fuel trim saved

All other things being equal (meaning you didn't knock a vacuum hose off etc.) this is the answer you are looking for. The computer has what's called a block learn function. It has to relearn your driving habits. Assuming you don't have a trouble code it should take care of the problem by doing nothing.

[LastDetail]

*update*
I reconnected the battery and left everything off - i.e. amps, head unit, air conditioning, fans, etc. - I started it up and drove about 30 minutes, driving pretty tame; for me. At stop lights it was very rough I kept thinking it was about to stall, then it would come back up to idle. Once it got through the rough spot at the bottom of the rpm it ran smoothly and I kept it around 35 mph with maybe a couple touches to 45. Never WOT (wide open throttle) or hard acceleration.
It is still idling rough though.
So you guys are saying that I should just drive it normally and that in a couple days this problem will just work itself out?
Thanks.

P.S. The response to this question has been just great, I put the same post on LS1Techdotcom and even though it got 8 or 9 views not a single person deigned to respond to such an apparently simple question. I love that nobody here is being an elitist auto guy and not getting down on me for not knowing very much about engine mechanics.

[harry444]

How old are the spark plug wires? if its running rough to the point that its going to stall then its not the computer trying to learn something. I would test the plug wires if it doesn't smooth out in a few hours

[LastDetail]

Originally Posted by harry444

How old are the spark plug wires? if its running rough to the point that its going to stall then its not the computer trying to learn something. I would test the plug wires if it doesn't smooth out in a few hours

You know its weird that you mentioned that. I just had (as in 3 days ago) my mechanic check the plugs and wires. He said that the wires were fine but that the plugs needed to be changed. I gave him the go-ahead and he changed out the spark plugs but used the original wires. This guy has never steered me wrong so I would imagine that the wires are fine. The only other thing that I can think it might be is the fuel pump. I am still on the original stock one at 107K.
Also my mechanic just did a full fuel system clean out, where he put an addititve in the fuel and a leak down through the intake manifold.