Date: Wed, 6 Feb 2013 16:00:32 -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.
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At 03:12 PM 2/6/2013, neil n wrote:
>Thanks Dick and David.
>
>Thanks *very* much for insights into what may have happened. Yes,
>maybe that solder joint was re heated. The insulated female terminal
>from 30 to relay shows what may be a slight small burn mark.
Well it certainly got hot enough to melt the solder around the
terminal, but that was from high resistance and arcing once the joint
had already gone bad. The flux residue around the solder pad also
suggests that it may have been reworked/reflowed -- i.e. repaired --
previously, which is what Dick was talking about. That would have
been done on the bench and not affected the female terminal.
>The replacement 109 relay is a different design; the pins go directly
>to the internal parts. Which begs a question:
>
>How do I know which way the relay box goes back on the relay base?
VW relays with PCBs have a pair of molded-in rails inside the cover,
that the board slides into to support it against overall
distortion/vibration. Failing to mount the cover in this orientation
will contribute to terminal failures.
>Since this was my first time at a swap (or work of this magnitude), I
>went with OEM wherever possible. I assumed the 109 relay had some more
>complex electrical "voodoo" going on so I made a point of using that
>part. Same with fuel pump relay. The ABA fuel pump relay has large
>30-87 terminals and a small 85 terminal (ECU) so a generic relay block
>was of no use. The 109 also has the small 85 pin. IIRC, I had been
>using a relay socket for the 109 along with a separate wire to 85 pin.
>Yes. Seems so. Image:
>
>https://sites.google.com/site/tubaneil2/PowerRelayDiagram.jpg I
>don't recall when or why I deleted this socket.
This relay according to the diagram on the side has an additional
component (likely a diode?) wired in parallel with the activating
coil. This would likely be to protect the electronics driving the
relay from being fried by the voltage pulse when the coil is
de-energised. You'll want to know what that component is before
replacing it with a generic relay (which you otherwise could by
taking a standard relay and connecting the 86 terminal to the 30
terminal. This particular relay is operated by switching the ground
lead rather than the hot lead of the coil. All this suggests to me
that it's being driven by an ECU output, is this correct?
>type. They will fit a FLAPS type generic relay socket. Both the Jetta
>Power Supply and Fuel Pump relays have a suppression component
>(appears to be a resistor) in parallel on 85 and 86 so I would make
>sure a substitute relay has same.
Ok, how specifically does it appear to be a resistor? What does it
look like, exactly? Any numbers, banded end, color bands, body
material, body color, body shape? I guess a parallel resistor could
be used to mitigate a voltage spike, I'm just not accustomed to the idea.
Yrs,
d