On Sat, 30 May 2020 08:22:22 -0000 (UTC), Smolley wrote:

snip

This morning after the engine fan had stopped I measured the
standing current across the open knife switch and was surprised to see the
meter was reading 3.26 amps. No wonder the battery flat!

How long did you leave it measuring for? When you connect the ammeter
you are effectively re making the circuit and it will then go though
any diagnostics etc until it goes into sleep mode.

Cheers, T i m