What are these wires for?

I got an 87 S10 4x4 and there is 2 wires running though the cab under the rubber flooring on the drivers side, a white and black one and they run up though the firewall and out through into the engine bay, the white one is burnt off and i'm tring to figure out what they are for?

blazer or truck? what size motor? do you have rear wipers? a diagram im looking at has a black and a white wires running through cab to rear wiper motor. black to rear window washer pump and white to wiper motor.
thats all i could find.

Its a Truck and theres no back wiper or cargo light

Oh and its a 2.8 in the truck

Does anyone know how to wire a 7 pin plug to an S10? I get the four pin plug, but I've got a blue wire fot the electric brakes and a black for charging the battery when connected to truck but don't know what wires under the back of the truck to wire them to. ANY help would be grateful.