Date:         Sun, 24 Feb 2008 13:32:08 -0800
Reply-To:     Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject:      Re: Bentley wiring diagram. Questions on how to read.
Comments: To: Mark Drillock <mdrillock@COX.NET>
In-Reply-To:  <47C1A584.8010208@cox.net>
Content-Type: text/plain; charset="us-ascii"

I have a question for you.
On this vehicle we're talking about here, 93 or 94 Jetta with ABA 2.0
engine...........on the HO2S  ( heated oxygen sensor )  Control Module,
there is a wire from that module to the ECU.
So evidently, or possibly, the ECU is involved in whether or no 02 heat is
on or not.

On a vanagon or a subaru the oxygen sensor/s get their heat circuit
energized anytime the key is on, i.e. whenever the ecu is powered up. In
other words 'full time' regardless. 

So my question is, what to do you think this connection is about ? 
My guess it that perhaps the ecu tells the H02S Module to heat the 02
sensors for the first say 15 minutes of running, and then doesn't have it
get heat power unless the 02 sensor cools down too much at another period in
that drive cycle. 
Any thoughts on that ? 

And also..........I 'would imagine' that if I wired one so it got 'regular
02 heat' through a normal relay , that the ECU would set a code perhaps from
not being able to 'see' that control module for 02 heat.
Any thoughts on that ? 
Thanx, 
Scott
Turbovans.


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mark Drillock
Sent: Sunday, February 24, 2008 9:13 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Bentley wiring diagram. Questions on how to read.

The HO2S relay is not part of the relay panel anyway, though it clips to
it externally. The Power relay and FP relays can be just standard relays
like all the waterboxers have in a separate relay box in the engine
compartment for those 2 functions. Far cleaner and simpler to use one of
those or duplicate it with a similar setup than to use the entire
vehicle relay panel from the engine donor. You only need 2 relays and a
fuse. The donor panel has provisions for 12 relays and 22 fuses, not
counting the external ones clipped to it.

Any externally mounted relay socket from the donor with a 53 or 24 relay
in it can be adapted for both FP and Power uses.

Mark

neil N wrote:
> Thanks. Yup. Getting it.
>
> It appears there are 3 relays needed. FP, HO2S, Power Relay. Hence
> part of my logic. Plus I figured if I could, I'd take the time to help
> make it easier for others doing a conversion using Motronic. i.e. they
> just pull the Jetta harness with all needed plugs, the fuse box, and
> when it's time to install, they just plug stuff in.
>
> IF in fact that's how it turns out. I'll be testing it out before I
> cut holes etc.
>
> For sure. Thanks for the warning. I'll make sure the FP relay is
> "safe". Getting its' signal from the ECM.
>
> Thanks again,
>
> Neil.
>