Date: Thu, 7 Feb 2013 01:30:37 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: No Start Cause: Relay Failure. PICS, Thoughts.
In-Reply-To: <CAB2RwfiRBUFUXQsAfKtS1CvJhvxqzoOJuueM5U5p5zLLonakUA@mail.g
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At 05:19 PM 2/6/2013, neil n wrote:
>Speaking of heat:
>
>https://lh6.googleusercontent.com/-vCPFjWDwWyw/URLRuT7232I/AAAAAAAAGzc/W6AxiYxxQgw/s640/109%2520relay%2520suppression%2520component.jpg
>
>70º C temp at coil windings. Interesting to me that's all. Relay is
>powered from a "12 VDC" wall wart. Voltage may be higher.
If it's an unregulated wart (most are) running
under stated load may be as much as 16-18 volts. 70C seems very hot to me.
>Yes. Order of events AFAIK: key to ign. on 15 + --> ECU. Energized
>ECU then sends - to power supply relay (109 relay). 109 relay sends
>+ to main + buss in harness for fuel injectors, ECU, etc.
>Slightly annotated diagram image:
>
>https://lh3.googleusercontent.com/-8GS0_Zk_uJE/UQRc-4jPHLI/AAAAAAAAGtA/jibwhoITrAU/s800/power%2520supply%2520relay.jpg
Ok. They had a relay socket meant to be used
with a relay driven from the positive side, and
an ECU with open-collector (a transistor with
emitter to ground, collector facing the outside
world) switching. It was worth it to them to
build a special relay with the relay 85 pin going
to the socket 86 pin (being used as an 85 circuit from the ECU).
>I may be wrong. Image of suppression component:
>
>https://lh6.googleusercontent.com/-vCPFjWDwWyw/URLRuT7232I/AAAAAAAAGzc/W6AxiYxxQgw/s640/109%2520relay%2520suppression%2520component.jpg
>
>At first glance looked like a resistor, but maybe not enough bands?
Unless der Deutsch were being particularly
imaginative that day, that's a quarter-watt
epoxy-dipped carbon- or metal-film resistor,
looks maybe slightly cooked. I can't read the
bands, looks like black brown?/green? black black
in the photo. Black green black would suggest 50R
>https://lh4.googleusercontent.com/-vrLtjwmz4xI/URLRueP8Q9I/AAAAAAAAGzg/Jh2bqF0A6jE/s720/109%2520relay%2520contact%2520close%2520up.jpg
The part you need to see is in between the
contact faces, not visible in the
photo. Incidentally, is that a NC contact on
top, or just a plate for the moving contact to bounce against?
>Not sure if VW wanted to save money on wire, and in the process make
>sure owners would have to purchase a "special" relays, but the 109 is
>obviously wired from 30 to one side of the coil, so only 3 external
>connections required.
If you know you're going to be switching from the
ground side and the coil is the same voltage as
the supply, makes things simpler/cheaper to use a
quarter inch of wire inside instead of n inches
and a terminal outside. Since you're using huge
volumes of them the setup cost for the relay doesn't add much.
> The fuel pump relay is similar. Diagram image:
>(ignore my annotations):
>
>https://lh5.googleusercontent.com/-qjVqWgmKgiA/UQLzz0KnCHI/AAAAAAAAGq8/dV79PgDqWQg/s720/ABA%2520swap%2520coil%2520wire%253F.jpg
At least they managed to find a socket that was
wired correctly for that one... ;-) Re the
annotations, I presume there's an 85 circuit
there somewhere, 'cause the relay as drawn won't
work unless they/you are connecting 85 internally
to the load, which is *really* cheating.
Yrs,
d
