So with 30 disconnected you still get the spike albeit random. That kind of rules out the clever circuitry in the switchback bulbs generating the spike so it still looks like it’s the relay.
What now….. Well I guess you need somebody that knows what they are talking about here and that’s not me
But thinking out loud and for the sake of a couple of quid you could try a relay that might uses less power. If you have used a 40 or 30 amp relay and for the sake of a couple of quid you could try a
smaller 20 amp relay? (and upgrade to speedy delivery for 60p
)
