I agree, I'm thinking ground. I don't know about 02, but 03 does not have flashers. It is totally controlled by the modules. The clicking noises which sound like the old flashers is a audio unit made to sound, you guessed it a flasher. FCM actually sends a signal to the turn signal relays and turns them on. And the audio unit inside the cab that sound like a flasher. Now of course I am speaking of our beloved 03's and I am clueless what the 02 does. Good luck...
Out of the 03 manual:
OPERATION
The instrument cluster monitors the multiplexed
multifunction switch operation. When the hazard
warning switch is activated, the instrument cluster
will send a J1850 bus message to the Front Control
Module (FCM), then activate the two turn signal indicators
and audible click in the instrument cluster.
The FCM will then activate the necessary relays in
the Power Distribution Center (PDC) to begin flashing
both the front and rear turn signal indicator
lamps.