Oil light and horn problems

Hi all was wondering if anyone has had this problem. My oil light keeps flashing even tho I have plenty of oil. I've replaced the connection on  both switches. Problem 2 is when ever I press my horn it stays on until I turn the car off. This is on a 1983 1.5 gx 

check/replace the horn relay to start with, if its the later blade fusebox its a 53 relay in slot 6:
http://www.clubgti.com/showthread.php?219775

for the other issue the oil light is triggered by the oil pressure switch in the side of the head, try replacing it. ideally go to vw as the pattern ones are not good quality.  have a good look at the wire to it make sure its not snapped somewhere further up. if you disconnect the wire and insulate it the light should no longer function. if it still comes on look at the clocks and wiring

its not a level sensor though its a pressure sensor, if chanign the switch doesnt help it may be your oil pressure is dropping. the threshhold is 0.3 bar at idle. low pressure at the head can be caused by blocked pickup, duff oil pump or worn cam bearings.

Thanks for the help was planning a weekend of working on the car so I'll add them to the list