I have a 91 na convertible 7 and my rpms dont work also my interior light wont turn on either sometimes when i start the car the rpms work for a small second but die down again i bought a brand new gauge cluster and it still doesnt work also swapped out to another ecu and still doesnt work, ontop of that everytime i open my ignition switch my parking lights go on automatically even when my light switch is on off position, can someone give me some assistance on what could be broken thanks!

 

Have you checked your METER fuse?

 

unhooked your trailing?

 

its a tachometer. the tach runs off of the trailing ignition.