For a 1997 GMC M11006, I've plans to fit a six-circuit isolator for the trailer wiring, so that any problems in the trailer not take out the van's lights in the process. I've ID'd all but two wires on the jack compartment stub harness (viz., 9 - 0.8 BR Tail Mrkr Lic; 18 - 1.0 YL, Left BT; 19 - 1.0 DGN, Right BT; 24 - 1.0 LGN, Back Up; 1642 - 2.0 OR, +Vcc UPFIT BAT; 1647 - 2.0 DBL, TRLR BRK DRIVE); only the 1.0 WH and 2.0 WH are yet to be identified in terms of the official General Motors circuit number table. Two connectors from Pollak are under consideration for the trailer receptacle: The 9-pin Fifth Wheel Utility Socket (P/N PK 12-907), and the 7-pin RV/Utility Socket (P/N PK 12-707E).

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In addition to ID's on the two white wires described above, would anyone have information on solid-state relays (not more than 35 A @ 12 VDC) suitable for the isolator and the sockets they would require? (My trailer set-up involves what is essentially a backport of the rear-body fuse and relay panel from the Chevrolet/GM City Express; the backport has ATM fuses for all trailer load feeds in the design.)