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2003 chevy trailblazer_ls
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Discussion Starter #1

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2003 chevy trailblazer_ls
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The second one (less expensive) is JUST a code reader. It cannot scan active (real time) engine data.

The first one (more expensive) will let you see real time data streams, plus codes. Codes in and of themselves are only helpful as a place to actually start with a proper diagnosis.

Everyone is enamored with codes as if they actually tell you what to fix -- nothing could be farther from the truth -- as anyone that has tried to deal with a problem based only on codes can tell you.

Codes plus real time PCM data stream let you see if, for instance, the O2 sensors are ACTUALLY reading data and sending that back to the PCM (indicating that they are working, and that the O2 code is because the readings are out of specification -- a problem somewhere upstream that is causing a rich or lean reading). The person with just a code reader is apt to install new O2 sensors in this scenario -- but still have the same problem after doing the work.

As you spend more money on scanners (versus code readers) they can do more for you. A Snap On or Genesis unit, for instance, will let you operate all of the electronic circuits on the vehicle (you can, for instance, turn on the electric fuel pump, operate the transmission solenoids, run the evap pump, etc.) and do a number of systems tests, including the all important ABS test and bleed routine. These type units will set a person back over $1000 (US) and can run to over $5000 (US) with all the bells and whistles (including wave form generator, 5 gas analyzer, etc.).
 

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2003 chevy trailblazer_ls
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Discussion Starter #3
Hoo I tought the second one could scan live data like they say on the web site "•Live Data Stream in Digital or Graph" or maybe it's not the same thing as the first one ??
 

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Looks like I didn't read far enough into the site. It can read some of the data streams. That would probably be good enough for the home mechanic just trying to diagnose his or her own vehicle. It doesn't show fuel trim and other data streams (at least the manual didn't indicate such) so the usefulness is still somewhat limited, but it does enough for common codes.
 
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