There isn't a single "transfer case relay" in the traditional sense on a Chevy Suburban K2500 (or most modern vehicles with electronically controlled transfer cases). The engagement of the transfer case is managed by a complex system involving the Body Control Module (BCM), the transfer case control module (often integrated into other modules), and various sensors. There's no one relay that solely controls it.
Troubleshooting a transfer case issue requires diagnostics using a scan tool to check for fault codes related to the transfer case actuator, its control module, or associated circuits. You won't find a relay labeled specifically for the transfer case. Any relays involved would be part of a larger electrical circuit for the system, not directly dedicated to the transfer case itself.
