Help Neeed it.....oil warning/tach issue

[thecubanfishy]

I have a pair of 1993 200s and on the port motor my tach won't read and my oil warning alarms won't turn off..????? I swapped the wiring to the starboard tach and it works fine,also both of my oil tanks are full...
I've looked all over for any corrosion on the wiring but found none,this started after I took that motor off to service the trim motor,the week before it had no issues

Thnx for any help in advance