I just changed the battery due to what I think is a dead battery. Everything went good, and the new battery fit perfect. But, when I started the car, it ran very rough and the check engine light came on. All I did was change a battery. What, if anything, do I need to do that will cure the problem.

Little more on the car, it has about 130k on it, and it has been running fine. My wife went out to start it the other day and it just clicked like the battery was done. I checked and it has been about 8 years since I changed it.

The only thing I can think of is I did not ground the terminals to each other before I put the new battery in. I have a 2005 Colorado, and I had to clamp the positive and negative together for a day to drain the extra energy out of the system so the computer would reset. Is that something I need to do here as well?

Any help would be appreciated.

Thanks,

Dino

 

Read the code(s) and report back.

 

Update to the problem. I thought to myself, well, let's just go and try touching the cables together and see what happens. It ran better, but the battery light came on and it was not charging. Great, now what did I do. So, I disconnected the battery and reconnected it again, and it all seems to be working right. The gauge is at about 14.5 or so, no battery light and it seems to be running smooth. The check engine light is on, and the alternator gauge will sometimes move to about 13.5 or so, but sporatically and not often. But it seems to be running ok now. Could it be that touching the cables together did the trick, and maybe I just did not have a good connected when I connected the cables to the battery? Gonna let it sit tonight and see how it runs in the morning.

I cannot believe that something so easy as changing a battery could be so difficult.

Any comments are welcome.

Thanks,

Dino

 

OK. Will do. At first the light would flash when I drove it around, but now it just stays solid. Does that make any difference?

 

If you disconnected the battery, the codes are likely gone.

 

But the Check Engine light is still on. I will check them, and let you know. These newfangled cars are a pain in the tail LOL

thanks for the help, I appreciate it.

D

 

If it is still on, then the PCM is still registering a fault with something. Get it scanned and let us know what the code is. Autozone, Advance Auto, and even my local NAPA will scan for free.

 

And the beat goes on. Wife drove the car around this morning, no problems but the CEL was still on. We get in it to go to Costco, light is off, charging at about 14 on the guage and running well. My brother is supposed to come by tonight with his scanner, so if the codes are saved even after the light goes off I will post them. But, does this sound anywhere near normal? I am guessing that if the CEL is off, that means the problem either got corrected or went away. Am I thinking correctly here?

Man, I miss the days of simple cars where if you changed a battery it did not lead to all these mysteries. LOL. Give me a 69 Camaro anyday.

Dino

 

OK, the code is P0300, Random/Multiple Cyl Misfires.

Funny thing, we tried to erase the code since the light is off, and my brothers machine could not erase it. This is the same code that the car had about 2 or 3 years ago when the plugs and wires needed to be changed at 100K. Could this be a leftover code? Is this something that is common when you change the battery?

Thanks to all for looking and to Swartik for the replies.

Dino

 

Some times codes are set on startup. The ECM asks all sensors a question and if it doesnt get the right answer a trouble code is set. It is called POST (power on self test). If a code is set this way one time, and (I think) the correct answers are returned 20 subsequent times the code is erased from history.

Sure wish my body worked that way!