I finally fitted the long sort after ignition switch to the port motor on my Johnson 30's, and we had some fun, the switch is totally different (although generic) in connection layout from the original and indeed some of the connections were numbered differently but we battled away and finally got the unit working properly. So...............
started the starboard motor and from turning the key the alarm sounds

The motor runs fine, water pumps out the tell tale on the head and also out of the vents on the back of the motor so it's not a temperature problem I think

apart from temperature alarm what other alarm is there? The motors are 1996 models