Plant wiring diagrams

[Wms]

Afternoon all!
I am a relatively new self employed mobile plant mechanic and am having electrical problems with a customers Thwaites.
Is there a good place to source wiring diagrams for plant?
Thanks in advance

 

[Gecko]

start at: www.classicmachinery.net (download section)
See if your model is there.

 

[Mick-the-fitter]

What model dumper is it, and what is the problem?