Date: Wed, 30 Jul 2014 13:08:17 -0700
Reply-To: Neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil N <musomuso@GMAIL.COM>
Subject: Re: Another question about O2 sensors..
In-Reply-To: <CAHTkEuJeA0E9jgtSW4iVdEzUh=6-W3vxkXTLq8NcSWHeEUM7QA@mail.gmail.com>
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> ..... the ECU most
> likely has a common ground that allows signals to be sent to it without
> having another ground wire going all the way back to the source...
I will speak somewhat ignorantly as I'm learning as I go but......
It varies depending on the engine management, but from what I've seen,
an ECU may have several ground wires. So inside the ECU, there may be
different discrete grounds for certain circuits. But I think you're on
the right track. The ECU components that process the O2 voltage output
need a positive and negative connection as does the O2 sensor itself.
All DC circuits require a positive and negative connection to
function. Exactly how various ECU ground pins connect to vehicle frame
(ground locations, physical routing of ground wires in a harness,
etc.) obviously depends on engine management, model year, market sold
etc.
The part that gets a little confusing for me is the shielding around
the O2 positive ("signal") wire. I understand it's function, but on
the 2.1 WBX it connects to an ECU pin and that ECU pin connects to
vehicle negative. That said, I'm sure this topic is covered in the
archives. Regardless, on a Mk2 Digifant 2 diagram I looked at, this
shield runs straight to ECU only. But that pin may have an internal
path to vehicle frame via another pin to wiring harness.
I know it's a PITA, and I make no claim to be completely adept at
reading them, ;) but for me it has paid 10 fold to learn.
On 7/30/14, Don Hanson <dhanson928@gmail.com> wrote:
> My assumption for connecting the single wire Bosch sensor like this, with
> just the one signal wire attached back to the ECU is that the ECU most
> likely has a common ground that allows signals to be sent to it without
> having another ground wire going all the way back to the source...
>
> ....I just don't know and I
> am unable to follow a complex wiring diagram to suss out the answer...
>
--
Neil n
Blog: tubaneil.blogspot.ca
'88 Westy http://tinyurl.com/c8rlw6p
'81 VanaJetta 2.0 "Jaco" http://tubaneil.googlepages.com/
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http://tinyurl.com/d7gd5ej