lane warning light error

Hi, I'm working for an aircraft developer that's starting now, and I'm equipped with 912 is sports. 

My aircraft has a problem that the warning light does not turn on when the ignition is checked

As a result of looking at various forums, I have seen an article that depending on the composition of the warning light, it may not be properly lit. 

Can you tell me the basic requirements for the lamp where the lane warning light is lit? 

Continuous inspection has already been done.

To illustrate the operation,


Before starting

No warning lights after battery operation
When the lane A switch is activated, the lane A and B are turned on at the same time and the warning lamp A is turned off 3 seconds later (off after function check)
The same is true when you turn on lane B switch.

After starting the engine

If the lane switch is switched off during the ignition check at 4000 RPM, the X of each indicator will be displayed on the screen, but the warning lamp will not illuminate.

I need your help.

Thank you in advance.