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Why am I logging B2S2 voltage while unplugged?

Old 04-05-2007, 06:29 PM
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Default Why am I logging B2S2 voltage while unplugged?

Using HPTuners I was going to wire my wideband through the rear O2 sensor harness as described here https://ls1tech.com/forums/showthrea...5&page=2&pp=20
But first as a test I added the O2 voltage B2S2 PID and scanned with nothing connected to the rear O2 plug.
Why am I getting voltage with nothing connected to the plug?

Last edited by 8a8mfh; 01-10-2008 at 07:37 PM.
Old 04-05-2007, 08:17 PM
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The PCM supplies a bias voltage of 450 mv to the O2 sensor high and low signal lines. When there in no O2 sensor connected to pull the voltage high or low, you will read the 450 mv bias voltage.
Old 04-07-2007, 02:37 PM
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Originally Posted by 2xLS1
The PCM supplies a bias voltage of 450 mv to the O2 sensor high and low signal lines. When there in no O2 sensor connected to pull the voltage high or low, you will read the 450 mv bias voltage.
The voltage seems to do the same thing even with the sensor plugged in and hanging in air.
Is this normal too?
So I can connect my LM-1 analog output up to the rear O2 plug and configure everything to read the wideband signal and it should work according to the information in the link?
Old 04-07-2007, 10:09 PM
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if it's plugged in and in the air there are no exhaust gasses going over it so nothing to meter so yes normal

as for hooking it up to the plug for the rear O2, that I'm not sure about...
Old 04-08-2007, 06:04 AM
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Originally Posted by horist
if it's plugged in and in the air there are no exhaust gasses going over it so nothing to meter so yes normal

as for hooking it up to the plug for the rear O2, that I'm not sure about...
It makes more sense to me than running it through the a/c pressure switch.

You put the link up in the sticky thread now you're not so sure about it?
Originally Posted by horist
good work... added as a sticky... we'll leave it up for a few days, then unsticky it (it's in the main FAQ)
https://ls1tech.com/forums/showthrea...5&page=2&pp=20
Old 04-08-2007, 02:18 PM
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Originally Posted by 8a8mfh
It makes more sense to me than running it through the a/c pressure switch.

You put the link up in the sticky thread now you're not so sure about it?


https://ls1tech.com/forums/showthrea...5&page=2&pp=20

It was stickied because of the original post
https://ls1tech.com/forums/pcm-diagnostics-tuning/496625-how-log-your-wideband-hptuners-without-eio.html (the sticky wasn't to post 20 as you are inferring)

Also you'll notice the quote you quoted was post 4 but you're talking about post 20 so please don't put words in my mouth

It works via the EGR or A/C pressure switch at 5 volts... I'm not sure about using the O2 sensors as I have not tested that method and have no need to test it, therefore there is no way for me to be sure.


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