[AT] O/T Tow truck OBD II question

[Doug Tallman]

Charlie, I'm not sure where to send you for the info your looking for. 
You might check into Motors Driveability manuals. They aren't cheap but 
they would have the trouble code charts and will give what parameters 
should be. Basically the graphs are just charting voltages. What make of 
interface are you using? I've been thinking of getting a program that I 
can use with the laptop.  Some of them do a lot more than the scan tool. 
Does yours have bidirectional communication with the PCM?  On the O2 
circuit, high voltage is low oxygen and low voltage is high oxygen 
content in the exhaust. In a lean situation you would expect the voltage 
to stay low. You would also need to check fuel trims to see how much is 
being added. The computer will add fuel to make the O2 voltages come 
back to cross the centerline. Fuel trims can be reset with bidirectional 
control to aid in diagnosis. Doug Tallman


charlie hill wrote:
> Thanks Steve,  the O2 numbers were really just an example of what kind of 
> data I'm looking at.  It's not setting a code that indicates an oxygen 
> sensor problem.
> However, there has to be a source of information out there related to the 
> ranges of all of the sensors along with some pictures of what the graphic 
> representations should look like.  That is primarily what I'd like to know.
>
> As for error codes the only one I'm having an issue with is a 0171, lean 
> condition, on Lynn's Buick.  I know how to find that problem.  I'll just 
> have to look a bit.
>
>
>   
>