May not be a relay?!?
This is the dome light in the headliner between the front seats???
I think I have 2002 wiring manuals at home and will try to check tonight.
The front headliner dome light and the rear cargo light are wired similarly - green-yellow (continuous power) + black-blue (switched power) + black (ground). 2002 may have different wire colors?!?
Reason why I know - I just replaced the SMB headliner with a stock van headliner with dome light and had to perform some wiring modifications.
There are some black relays under the steering column a few inches behind the trim piece at the drivers knees.