If the battery was not disconnected when you were washing you could have shorted out any number of electrical sensors/circuits, this is why I rarely wash the engine, if it was a carbed v8 with a couple of sensors sure but a caddy has loads of electrics, I take the engine cover off and wipe it, that's it.
I think your best bet now is to bend over and take it to the caddy dealership and hope that they use lots of lubrication when they hand you the bill.