1994 Chevrolet Blazer Owner's Manual - Page 134
1994 Chevrolet Blazer Manual
Page 134 highlights
Trailer Wiring Harness Your vehicle may haveeither a 5-wire or 7-wire harness. The light duty trailer wiring isa 5-wire harness assembly taped and bundled at the left corner of the vehicle interior, next to the endgate. The harness has no connector, and you should have a qualified service person wire your harness for you. It must be routed out your vehicle and attachedso that of the trailer or the body won't pull it. The heavy duty trailer wiring isa 7-wire harness assembly consisting of a 5-wire harness and a 2-wire harness taped together and stored under the vehicle, along the rear frame crossmember. It has a 30-amp feed wire with an inline fuse located by the junction block. See "Fuses and Circuit Breakers" in the Index. Both the 5-wire harness and the 2-wire harness have no connector and should be wired by a qualified service person. Attach the harnessto the trailer, then tape or strap it to your vehicle's frame rail. Be sure you leave it loose enough so the wiring doesn't bendor break, but not so loose that it drags on the ground. Store the harness in its original place. Wrap the harness together and tie it neatly so it won't be damaged. 2-80