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2005 chevy trailblazer_ls_ext
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Discussion Starter · #1 ·
Hello I had to replace my battery today. I got the gold one from autozone. its a 800 cold cranking amp. the stock one was 600. I went to crank it over and it would start fine then shut of the engine right away. What would the problem be? thanks.
 

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Did the engine "shut off" or just die? The engine computer may have made so many compenations for worn plugs, dirty throttle body, etc. that the reset to the defaults when the battery was disconnected has everything so far out of adjustment that the engine doesn't like it. The computer has to relearn and make adjustments or the engine needs a tuneup.
 

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Western Canada Chapter
2003
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6,421 Posts
Hello I had to replace my battery today. I got the gold one from autozone. its a 800 cold cranking amp. the stock one was 600. I went to crank it over and it would start fine then shut of the engine right away. What would the problem be? thanks.
When the battery is disconnected the PCM resets. The PCM, under normal running conditions, will make gradual changes to compensate for the gradual fouling of the throttle body.

Clean the throttle body and the PCM and the throttle body will have matching parameters. Fresh calibrations in the PCM and a fresh throttle body.
 

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2005 chevy trailblazer_lt
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So why did you have to replace the battery?

Just curious. Ignition switch failure isn't uncommon on these. Thought maybe it was, and still is the problem. Or maybe it was the battery and now it's the switch. Coincidences like that happen - just to mislead us!!

If it's the computer needing to re-learn, I'd think the motor would stumble a little. If it's something like the switch, it would just die - like you turned the key off. Not sure which it's doing.:undecided
 

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2004 gmc
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I agree. A good crank followed by failure to run is most often the ignition switch, second cause would be a passlock security system problem that disables the fuel pump. Do you ever see the security light on the dash?
 

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2005 chevy trailblazer_ls_ext
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Discussion Starter · #8 ·
i replaced battery because when i went to start my TB it did the clicking and all the lighting was dim like the batt was about to go. Since the morning ive driving around it seemed to work good. the idle is up. Now the problem is when the AC is on the idle drops to almost stalling. Tomorrow I will clean the Throttle body and change the spark plugs. Thank you for all your help.
 

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i replaced battery because when i went to start my TB it did the clicking and all the lighting was dim like the batt was about to go. Since the morning ive driving around it seemed to work good. the idle is up. Now the problem is when the AC is on the idle drops to almost stalling. Tomorrow I will clean the Throttle body and change the spark plugs. Thank you for all your help.
The low idle with the a/c on is definitely the throttle body being dirty. If I had a dollar for everyone that's ever had this problem . . . :D
 

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2004 chevy trailblazer_lt
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Throttle body is a good one for sure, then after that check for any pending codes if you can get your hands on a code reader. After that, tune up everything you can if it needs to be done (search around here), and if no go yet then the switch would be a good place to look, and its not expensive either.

Good Luck!,
Keith

(and if you are still looking for how to clean your TB, check my sig)
 
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