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/
Pin 20 Composite video input/Sync 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.