Did you pull the fuses and check them with a meter? Visual is not good enough, and you have to at least pull one side of the fuse out to check them with a meter.

Also check the connectors for the GI for burns, melting, or hacks.

Check the values also and make sure they are in-spec.

Check voltages starting at one end, and work your way to the other. Start at the transformer or a bulb socket, doesn't matter which. Eventually you'll find the failed component(s).

If you have a bulb shorted out in a socket, it will take out All of the GI. I know, as it happened to me last week. Good luck~Spooky

Yes, but that should take out the GI fuse too.

I had the same issue when I changed all of the bulbs to #47 and spent time checking everything. I had previously checked the 20A fuse & it had tested + on my fusetester. However, although the fuse appeared in perfect shape, I decided to check for continuity and it was negative. Replaced the fuse & GI lights worked. It is possible that there may have been a short caused by me (with 1 of the sockets) and I checked all sockets prior to the fuse replacement. I hope you solve your issue as it is very frustrating when there are only a couple of reasons that the GI lights will not work.

Pull your fuse and check for voltage right at the incoming side of the fuse block.

If you don't have voltage there, then you know the problem is before the block.

If you DO have voltage there, then you move along the GI and find it.

These are your friends for this kind of work:

fuse breaker.jpg