Seems to be associated with starter motor problems and / or the crank sensor, rather than the solenoid [or celinoide :-) ]
Check these threads out:
https://www.honestjohn.co.uk/forum/post/index.htm?t=66222
http://www.renaultforums.co.uk/14-engines/137838-05-renault-trafic-1-9-wont-start.html
http://www.bba-reman.com/forums/Topic103765.aspx
Plus, do a Google search for something like: "Renault traffic 1.9 DCI, van wont start with key but will start with tow"
acp, April 2017