Lane B warning light

Hi,

I have a question about the Lane B light being odd.

When we turn off Lane A, we get the Lane A warning lamp and we lose the expected gauges on the EFIS that are tied to the Lane A ECU.

When we turn Lane A back on, the Lane A warning lamp stays on for a little bit longer as it starts up the ECU, and then goes out as expected.

That's all great.

But when I turn off Lane B, we do NOT get the Lane B warning lamp. We do lose the expected Lane B gauges so we know the Lane is turning off. The Lane B light stays out.

When we turn Lane B back on, the Lane B warning lamp lights up and it starts lit up for a few seconds as it goes through it's boot up checks and then it goes out. This proves the Lane B warning lamp works.

Why don't we get the Lane B warning lamp when Lane B is off though?

Engine is otherwise running fine during this process on Lane A, B and both. No errors are shown when both Lanes are on.

We have recently pulled our aircraft panel out, and have reinstalled it after some work on the aircraft. I'm not sure this is related, but it's the only change we have made and I'm sure it wasn't doing this prior to this.

Thanks.