Outer Limits 4x4 Board

i was just installing my dual battery in my diesel patrol,

i tapped for ignition into the wiper motor for my solenoid,
i earthed out the solenoid,
i ran from the power of batt no 1 to the solenoid,
ran from solenoid to the power of batt no 2,
go to earth the batt no 2 and kaboom sparks larger than new years fly everywhere,this is with all ignition off

WHAT THE FCUK WENT WRONG

does the solinoid have 2x big terminals , and 2x small terminals>??
wich have you powered, and wich have you earthed???

yeah, shes all done now, one of the battery cables was touching the solenoid