Usually get this on my escort van and its a dodgy connection to the lights (wire or plug not on properly)
Id check connection to the stalk aswell though and the earths especially if you've had it sprayed. Spray some contact spray on the connections.

Rev counter could be linked so would suggest an earth problem or connection behind dash somewhere

As for locking, mine does this when one door isnt shut properly so make sure you doors shut flush and straight