Where does the single black wire with orange plug go off mof my steering column on 94 chevy 1500

Sounds like your steering column wiring harness has come disconnected. Check the condition of the connector, which will be located between the brake light switch and the instrument cluster, plugging into your steering column. Also, check the ground connection at the steering column (single black wire).

1988 swb chevy 1500 steering column wiring diagram Google Search
This should help!

yes but you will have some extra wires

This is only an idea-pull column shifter boot-you will notice a ORANGE wrapped wire which runs from the button on the shifter down toward the steering column. This is the Tow/haul wire. The way this is positioned on the steering column will cause the wire to be pinched when ever the steering wheel is adjusted. This pinching can cause a short or cause the tow/haul not to work at all. NOTE: Inside this orange wire wrap are two very fine fiber wires. Be careful and good luck

I would say that you have the wrong steering column.

12V CONSTANT WIRE RED and PINK/BLACK Ignition harness
12V IGNITION WIRE DARK BLUE Ignition harness
12V ACCESSORY WIRE BLACK/ORANGE Ignition harness
STARTER WIRE YELLOW Ignition harness
PARKING LIGHTS (+) BLACK/YELLOW At Headlight switch
POWER DOOR LOCK (5-wire reverse polarity) ORANGE/PURPLE Harness Coming Into Vehicle From Driver's
Door
POWER DOOR UNLOCK (5-wire reverse
polarity)
PINK/PURPLE Harness Coming Into Vehicle From Driver's
Door
DOOR TRIGGER (-) YELLOW/BLACK At Headlight Switch
DOMELIGHT SUPERVISION (-) Use door trigger
TRUNK TRIGGER (-) GRAY/BLACK At Light In Trunk
TACHOMETER WIRE TAN/BLUE or BLACK/GRAY At Ignition Coil
BRAKE WIRE (+) WHITE/BROWN At Brake Pedal Switch
HORN TRIGGER (-) BLACK/RED Harness Coming From Steering Wheel At
Column
CAUTION! SRS airbag wires are not enclosed in protective loom at the steering column. They are a twisted pair of wires that run with rest of
ignition harness. Be careful not to cut or probe these wires.

Radio:

(Black plug)
Rear Right speaker -: Blue w/White stripe
Rear Left speaker -: Brown w/Yellow stripe
Front Right +: Purple
Front Left +: Dark Green
Rear Right speaker +: Blue w/Orange Stripe
Rear Left speaker +: Brown w/Blue Stripe
Power Antenna/Amp: White
(Gray Plug)
+12v battery wire: Pink or Pink w/White Stripe
+12v Ignition wire: Red w/ White Stripe
Front Right speaker -: Blue w/ Red Stripe
Front Left speaker -: Brown w/ Red Stripe

Possibly a short in the directional switch in the steering wheel. Your brake lights use the same filament as the turn signals, so the brake light wiring goes thru the directional switch. Does one wire from the brake light switch go up the steering column?

the horn wire is under the steering column with the turn signal switch molley plug and its a single black/ blk with white stripe wire just hook that to the other wire you found

pick up a chilton book from chapters indago and check the diagrams they might be similar but i believe the wiring is a lot different '
it is likely you will need both manules

95-97 blazer or 94-97 S-10
12volts red (there will be 2)+ ignition harness
Starter purple or yellow + ignition harness
Ignition pink + ignition harness
Second Ignition white or pink/white + ignition harness
Accessory orange + ignition harness
Power Lock lt. blue + either kick panel
Power Unlock white + either kick panel
Lock Motor gray drivers kick panel
Unlock Motor tan drivers kick panel
Parking Lights+ brown switch or rear harness
Door Trigger white - keyless module
Dome Supervision use door trigger
Trunk/Hatch Pin tied in with doors
Trunk/Hatch Release black/white + switch or keyless
Tachometer white AC ECM
Brake Wire white + at brake pedal switch
Parking Brake black at the pedal
Horn Trigger black - steering column