Where is the transfer case control module located?

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I drive a 96 GMC Surburban K1500 SLE 5.7 . Had my transfer case serviced not long ago because of a grinding sound. My 4 wheel drive hasn't worked in years. 2hi indicator is not illuminated and get no response from switches when in drive or lower gears. Indicator lights illuminate on ignition then shut off. Switches do respond in neutral but no shifting, only 4hi and 4lo illumination together. Tried tccm code reset but no luck. Need direction.