PEUGEOT ALL MODELS WIRING DIAGRAMS - GENERAL (autoelectric.ru)

You don't use wire colour, mainly use pin numbers. You can find that on the connectors, inside lip will have numbers printed.

 

i was dismayed to see that the wire colours on the wire diagram was coded with numbers and even no colour on the wiring diagram as illustrated in the attachment below

The wires have the (generally) 4 digit code printed on them - it's not a colour reference. That is, each individual wire will have a code printed on it, as per your attachment.

Apart from that, connectors are referenced by colour, ie. "18V NR" is an 18 pin Black (Noir in French) connector.

This link is a little dated but generally explains everything in great detail.

 

assume i need to probe crankshaft sensor signal directly and i have already identified the crankshaft sensor connector digit code as 1313 as shown ,how will i be able to identify the signal directly out of the 3 other terminal as i dont want to be wasting time messing around with the reference voltage voltage and ground terminal as that is the problem i am currently facing .