Date:         Fri, 14 Mar 2003 18:17:14 -0500
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: O2 Sensor Checking??
Comments: To: Doss88Wkndr@AOL.COM
In-Reply-To:  <129.256747b5.2ba3634e@aol.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 11:54 AM 3/14/2003, Brian Doss wrote:
>how to go about it.  Some of my questions would be; 1) what kind of voltmeter
>do I need.

DMM (digital multimeter) with 10 megohm input impedance -- or an
oscilloscope with x10 probes to give 10 megohm inpug impedance.  Or Ken's
little circuit board.  The scope or Ken's board will give a real-time
display; the DMM will also as long as the signal is stable over half a
second or so.  As soon as the ECU starts its closed-lop routine the DMM
will give random-appearing readings -- but if some of them are above half a
volt and some below, the circuit is working.  You won't find a lazy (i.e.
slow-responding) sensor with the DMM though, I don't think.

>  2) how do I turn it on?

Discover its secret fetishes and parade them in front of it, keeping them
tantalizingly just out of reach.

>  3) what setting do I put it on

2-volt DC scale for DMM, 200mv/division for scope.

>4) after I
>disconnect the plug to the sensor, what leads am I looking for, which side?

You don't *necessarily* disconnect it at all -- depends on what you're
looking for.  If you want to see the ECU in closed-loop mode you leave it
connected.  Measure between the single lead (green coming from the harness)
and ground.  That lead has a double-female-spade arrangement with a
double-male adapter in between -- slide the boot back until you can connect
to the wire.  DO NOT put a pin through the green wire as it's coax and
you'll short it out.

david

--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"