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
>
>70� 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