Thought this may be of some help.

How a Scart is wired

Pin 1 Audio output (right)

Pin 2 Audio input (right)

Pin 3 Audio output (left)

Pin 4 Audio ground

Pin 5 Blue ground/Chroma input ground

Pin 6 Audio input (left)

Pin 7 Blue/Chroma input

Pin 8 Widescreen function switching (This is the pin the switches your TV to AV automatically)

Pin 9 Green ground

Pin 10 D²B input

Pin 11 Green

Pin 12 D²B output

Pin 13 Red ground/Chroma ground

Pin 14 D²B ground

Pin 15 Red/Chroma

Pin 16 Fast switching

Pin 17 Composite video output ground/Sync output ground/

Luminance output ground

Pin 18 Composite video input ground/Sync input ground/

Fast switching ground/Luminance input ground

Pin 19 Composite video output/Sync output/

Luminance output

Pin 20 Composite video input/Sync input/

Luminance input

Pin 21 Common ground

Blanking and switching

Two pins provide switching signals.

Pin 8, the function switching pin, carries a low frequency (less than 50 Hz) signal from the source that indicates the type of video present.

0 V-2 V means no signal, or internal bypass

4.5 V-7 V (nominal 6 V) means a widescreen (16:9) signal

9.5 V-12 V (nominal 12 V) means a normal (4:3) signal

Pin 16, the fast switching pin, carries a signal from the source that indicates that the signal is either RGB or composite.

0 V-0.4 V means composite.

1 V-3 V (nominal 1 V) means RGB only.

The original specification defined pin 16 as fast blanking, a high frequency (up to 3 MHz) signal that blanked the composite video. The RGB inputs were always active and the fast blanking signal 'punches holes' in the composite video. The SCART connector uses this to overlay subtitles from an external Teletext decoder.

0 V-0.4 V means composite with a transparent RGB overlay.

1 V-3 V (nominal 1 V) RGB only.

There is no switching signal to indicate S-Video. Some TVs can auto detect the presence of the S-Video signal but more commonly the S-Video input needs to be manually selected.