Diagnostics

[ben swann]

Steve,

Thanks for the comprehensive reply.  I got the information I needed
from it to clarify the SJM diagram.

I already have the adapter made up - three connectors scrounged from
rear window brake light harness, one to each of the underdash
connetors.  I have a push button switch to trigger into diags mode and
an led (actually a rocker switch with built in light).

I'll se how it works tommorrow.

What is the source and cost of Prodiag?

Thanks again,

Ben

[----- Original Message -----
From: Steve Eiche <seiche at shadetreesoftware.com>
Date: Thursday, May 8, 2003 10:38 pm
Subject: Re: Diagnostics
Ben,
Yes, you can run diagnostic and check for stored codes without using a
scan tool.  It is really quite simple.  If you car has a check engine
light, there is no need to use an LED.  If your car does not have the
light, the socket should be there so all you have to do is plug a bulb
in.  If you cannot find the socket behind the dash (behind the three
small gauges on the right), you can use an LED and jumper as shown on
Scott Mockry's web site (http://www.sjmautotechnik.com/ecuf20v.html) or
the Bentley manual.  If you have the light, you only need a jumper
wire.
  As long as you don't short the two wires on the black plug (12V and
ground), you really can't hurt anything.

Basically, to run the tests, put a jumper from the L line (brown
connector, connection away from the clip) to ground (black connector,
connetion away from the clip or any ground) for 5 seconds.  This
initiates the blink code fault display on the check engine light if the
engine is running, or the output tests if it is not.  If you do not
have a check engine light, you can connect an LED test light between
the connection on the blue plug (the only wire there, connection close
to the clip) and 12V (black plug, connection closest to clip or any 12V
source).

Having a scan tool like our ProDiag is nice, especially on the newer
cars with more complete diagnostics or if you need to track down a
tough problem with requires you to monitor measuring blocks, but you
can easily make do with just the jumper on a 3B.

HTH!

Steve Eiche
Shade Tree Software, LLC
www.shadetreesoftware.com]