Thanks Guys.....I will look for yet another wire that is not used and goes back there.  Possibly oil light?   
 > Date: Tue, 27 Mar 2012 12:47:39 -0400
> From: dbeierl@ATTGLOBAL.NET
> Subject: Re: OXS wire in black box engine compartment
> To: vanagon@GERRY.VANAGON.COM
> 
> At 12:22 PM 3/27/2012, Jamie Fitterer wrote:
> >Hey everyone, I Have a 84 westy that I have done a conversion in and
> >would like to reuse the OXS light if possible as the new Check
> >engine light.    I am a novice to tihs electric stuff and was hoping
> >someone could let me know what Wire to hook up to in the rear black
> >box to ride to the OXS sensor light?    Thanks in advance.  I
> >apologize to the purest ahead of
> >time.
> 
> It doesn't go back there.  Everything is in the panel and the timer
> box connected to the speedo cable.  Note that the OXS and ALT lights
> are cross-connected (to provide a bulb check for OXS) so that any
> time the ALT light is on, the OXS light will also be on.
> 
> If you search back messages at subaruvanagon@yahoogroups.com (may
> have to join?) there will probably be precise instructions.  Note
> that that group is strictly for Subaru conversions, and they stay
> strictly on topic.
> 
> Yours,
> David