I am not sure whats all integrated in there, but I heard that this is what you have to replace if your dome light are acting up. If they will sometimes turn on or you have to hit the light to make it work.
I got an extra one from my 1J clip so I might just install it anyways and find out.
i was having a problem after i installed my alram with the dome lights. Since the alarm senses the dome light to see if a door is open, then that meant that my door portion of the alarm would not work because the light didn't turn on.
After much searching and very unclear information i found out what i had to do.
Get the integration relay from behind the fuse panel that is in the drivers kickpanel and open it up and find the resistor and replace it with a peice or wire i welded in. Once i did that then my dome light worked and the dim feature did also and my alarm is now fully operational.
in both cases it sond slike a ground issue, the light is grounded by using the screw you hold it on with. Toyota could have been a bit less cheesy in this area but oh well. If you're feeling brave then check the relay, just expect to be in the foot area for a good 30 mins lol