BTW: The LED with the slightly wider leg is the negative....just look at the
base of the legs where it's formed into the plastic and you'll see the
difference.  (See Bentley manual on page 90.5)
Karl Batzler
La Quinta, CA
-----Original Message-----
From: YauMan Chan <YauMan@CCHEM.BERKELEY.EDU>
To: vanagon@VANAGON.COM <vanagon@VANAGON.COM>
Date: Friday, October 16, 1998 8:15 AM
Subject: Re: Alternator warning light

Earl,

When an LED comes out of the LED stamping machine, the longer leg is the
anode and the short is the cathode.  But when it get installed, they are
clipped... so there is no easy way to tell.  But fear not.  LED cannot be
destroyed if you put in it backward.. it just won't light up.  Just turn it
around and it will work again.  If you want to test it first, you can use an
ohmeter.  Measure the resistance one way, and then reverse the leads and
measure again. The "forward" direction is the low resistence configuration.
remember which leg had the red lead from the ohmmeter.. that's the leg that
should be positive.

Caution.  If you don't have an ohmmeter, and wants to test which way to
light up, don't just connect it to a battery.  It will survive a reverse
direction, ie no light up direction, but in the corrrect forward direction
(light up) there will be too much current and may blow the led.  LED
circuits have current limiting resisters so it is much safer to test the LED
in circuit rather than putting it across a battery unless you put something
like a 2K ohm resister in series.

Yau-Man Chan
87 GL

>>> Earl Smith <earlsmit@ISLANDNET.COM> 10/15 7:34 PM >>>
Is there any discussion in the archives about how this system is supposed to
operate?  Hayes manual is careful to point out that the LED has a negative
and positive terminal but nowhere does it tell one which SOCKET is positive
or negative.

Earl from Sunny Sooke
84 ex-California Vanagon