the pcv hose heater is conencted to Igntion on voltage I beleive.
( it's a small stand-alone harness that can be retrofitted to any waterboxer
engine easily, btw )

I didn't measure oxygen sensor heater current draw,
but I wanted to make sure it was on something that could take a nice draw,
just in case.
I have it powered off the fuel pump relay output.
Doesn't seem to me that the pcv hose heater element draws would current, but
I havn't measure it either. yet.
thanks for your comments.
If wired to Ignition +, I  suppose HV noise could get into the sensr heater
circuit ......
but seems to me unlikely that it could affect sensor operation - but that
might be possible.   Anything is possible in electronics.
thanks ,
scott

----- Original Message -----
From: "David Beierl" <dbeierl@attglobal.net>
To: "Scott Daniel - Turbovans" <scottdaniel@turbovans.com>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, September 10, 2009 8:56 PM
Subject: Re: Re: O2 Sensor wire connection (wiring harness end - 2.1)

> At 11:40 PM 9/10/2009, Scott Daniel  - Turbovans wrote:
>>Here's an electrical question for ya David.
>>When fitting a heated oxygen sensor to a vanagon that had just a
>>non-heated single wire one,
>>what is the proper place to connect the heater wire to ? - the wire that
>>will power the heating element in the sensor.
>
> My first thought would be to check the draw of the vent hose heater and
> the sensor, and if they'd both fit comfortably into five amps then power
> it off that.  It's handy in the connection box and it's fused (as is the
> rest of my nice "Approved by Scott Daniel" harness now, as well).  :-)
>
> Next one I'd think of though would be off the ECU power.
>
> I wouldn't *expect* any problem from connecting to the coil B+, but
> conceivably getting the wire too close to the HV stuff might capture some
> noise that could perhaps upset the sensor.
>
> :-)
> d