Can anyone tell me the next step and if I've gone down the right route.

had a starter fitted 4 months ago,

vans been fine 

2 week ago  it wouldn't start after an hour of driving after I came out of a shop. Sat there trying it, nothing at all, immobiliser light was ok, but no crank from starter. Rang a friend to ask his advice and it started while he was on the phone.

Yesterday it's happens again but can't get it started

 

12.42 across battery.

this drops to 12.17 with ignition full. Does this prove ignition switch ok.

fuses inside are all ok

havent checked under bonnet ones cos Haynes showing different layout.

is either side of the starter next?

ive jacked it up but need some advice.

get me back to work peeps.

thanks in advance

Battery should be above 12.6v and needs to hold 12.9v to properly charge. Then above 13.5 when alternator is charging it.

How old is the battery? I bet it's probably time for a change.

Does the starter motor clunk when you turn key (the solenoid moving).

are wires on starter properly. If no solenoid clunk pay particular attention to the thinner wire which comes from the ignition switch to energise the solenoid.  Use voltmeter to check if power there when you turn the key

Could be faulty ignition switch (I have known this) , this can be checked by accessing the wires on back of ignition switch and bridging the wires that would connect when you turn the key.

was it a brand new starter motor or a recon.  I have known some recon starters to be iffy (admittedly many years ago). I think some cheap ones did not have much of a recon, more of a clean and polish externally rather than new parts inside. So there is a chance it could be a faulty starter motor

voltage does sound a bit low.  what you did does not prove ignition switch ok. it proves that the switch connects power for the main electrics, it does not prove the contacts in the switch for starter operation are ok.   Although battery voltage sounds a bit low, if it was just a battery problem I would expect you to get some clicks or clunks at least when you operate the ignition  key to the sterter position