Hello and Welcome to justanswer...
If the immobilser LED is staying on - as in permanently when switched on - then there is a fault in the system - and I'm afraid the only way forward is to have the van connected to a diagnostic machine to have the system interrogated , likely re programmed due to the battery having been off for so long.
The light should only come on for 3 secs... longer or permanent or flashing...results in the above course of action I'm afraid.
The only ,one thing you can try
..is to disconnect the battery - clamp the battery cable ends (lead terminals - not the battery itself) together...and keep them like this for 15 mins -- Then disconnect them - leave them off the battery for another 15 mins - then reconnect and re try .
If you still have the light problem ...aim the key at the receiver and press . cycle the buttons several times -- Sometimes - this will work and is worth a try.
If nether procedures work - it will need to go on the diagnostic machine to be reprogrammed / re set...
I Sincerely XXXXX XXXXX have helped you - Please ask me if you need more help...
Kind Rgds, MIKE
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