Can the orange/white illumination wire from the factory plug be tied into the red or yellow wire? My harness does not have any other available wires.

I found a wiring diagram for the 2005 Hyundai Elantra that might be helpful . According to the diagram, the color codes for the factory wiring harness are as follows:

Wire Color Function
Orange/Black 12V Constant
Yellow 12V Accessory
Black Ground
Blue/Black Power Antenna
Green/Orange Illumination
Brown/White Left Front Speaker (+)
Black/White Left Front Speaker (-)
Brown/Yellow Right Front Speaker (+)
Black/Yellow Right Front Speaker (-)
Brown/Red Left Rear Speaker (+)
Black/Red Left Rear Speaker (-)
Brown/White Right Rear Speaker (+)
Black/White Right Rear Speaker (-)
If you don't have a plug on your factory wiring harness, you can hardwire it by connecting each wire to its corresponding wire on your new stereo. You can use crimp caps or soldering to make the connections

. If you're not comfortable with hardwiring, you may want to consider purchasing an aftermarket wiring harness that clips onto the factory harness you removed off the rear of your factory radio during its removal. This will make it easier to connect your new stereo to your car's electrical system .Hyundai Radio Wiring Color Codes - Radio Codes Calculator

SEE ALSO IF YOU CAN GET HELP AT LINK BELOW
http://www.2carpros.com/makes/ford/f150.htm

ITEM - WIRE COLOR - POLARITY - WIRE LOCATION
12V - red - POSITIVE - ignition harness
STARTER - white - POSITIVE - ignition harness
IGNITION - red - POSITIVE - ignition harness
ACCESSORY - red - POSITIVE - ignition harness
SECOND ACCESSORY - yellow - POSITIVE - ignition harness
BRAKE WIRE - white - POSITIVE - brake pedal switch
RADIO 12V - red - POSITIVE - radio
RADIO GROUND - black - NEGATIVE - radio
RADIO SWITCH - yellow - POSITIVE - radio
RADIO ILLUMINATE - pink - POSITIVE - radio
POWER ANTENNA - gray/orange - POSITIVE - radio
LF SPEAKER - white - brown - radio
RF SPEAKER - green - orange - radio
LR SPEAKER - yellow - black - radio
RR SPEAKER - orange - blue - radio

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Your vehicle radio color codes below;

Radio 12v blue + radio harness
Radio Ground (chassis)
Radio Ignition pink + radio harness
Radio Illumination yellow/red + radio harness
Factory Amp Turn-on blue/white or pink + radio harness
Power Antenna N/A
LF Speaker +/- purple - green/yellow +,- radio harness or amp under rear deck
RF Speaker +/- brown - brown/white +,- radio harness or amp under rear deck
LR Speaker +/- orange - black/pink +,- radio harness
Notes: On vehicles with premium audio systems, the LR speaker wires are yellow/green - white/orange.
RR Speaker +/- gray - gray/red +,- radio harness
Notes: On vehicles with premium audio systems, the RR speaker wires are red/black - gray/blue.

This should help you out. Good Luck.
Radio Ground black - radio harness
Radio Ignition pink + radio harness
Radio Illumination blue/black + radio harness
Factory Amp Turn-on N/A
Power Antenna green/black + radio harness
LF Speaker +/- blue/red - yellow/black +,- radio harness
RF Speaker +/- black - yellow +,- radio harness
LR Speaker +/- brown - white +,- radio harness
RR Speaker +/- green/orange - blue/orange +,- radio harness

It all depends on the Kia model but here is a diagram to get started with.

Radio Wiring Information:[B/]
Radio 12v red + radio harness
Radio Ground black - radio harness
Radio Ignition orange + radio harness
Radio Illumination red/orange + radio harness
Factory Amp Turn-on pink + radio harness
Power Antenna white + radio harness
LF Speaker +/- black - yellow +,- radio harness or amp under driv seat
RF Speaker +/- red - blue +,- radio harness or amp under driv seat
LR Speaker +/- orange - green +,- radio harness or amp under driv seat
RR Speaker +/- white - brown +,- radio harness or amp under driv seat

Pin --- Color --- Stripe --- Function

Harness 1

1 --- White --- Black --- Left front +
2 --- Gray --- Black --- Left front -
3 --- White --- Purple --- Left rear +
4 --- Gray --- White --- Left rear -
5 --- White --- Red --- Right front +
6 --- Gray --- Red --- Right front -
7 --- White --- (none) --- Right rear +
8 --- Gray --- (none) --- Right rear -

Harness 2

1 --- (not used)
2 --- Black --- Green --- Radio Ground
3 --- (not used)
4 --- Orange (thin) --- Black --- Radio Illumination
5 --- Green --- Yellow --- Radio switch
6 --- Black --- Yellow --- Radio Ground
7 --- Orange (thick) --- Black --- Radio 12V

Harness 3

1 --- White --- Green --- Speed sensor
2 --- (not used)
3 --- (not used)
4 --- (not used)
5 --- (not used)
6 --- (not used)

Battery WHITE/YELLOW (+) RADIO HARNESS
Accesory WHITE/RED (+) RADIO HARNESS
Ground BLACK (-) RADIO HARNESS
Illumination RED/BLACK (+) RADIO HARNESS
Dimmer RED (-) RADIO HARNESS
Power Antenna YELLOW/WHITE (+) RADIO HARNESS
Amp Turn On YELLOW/WHITE (+) RADIO HARNESS
LF Speaker (+) WHITE
LF Speaker (-) ORANGE
RF Speaker (+) YELLOW
RF Speaker (-) BROWN
LR Speaker (+) RED
LR Speaker (-) GREEN
RR Speaker (+) BLUE
RR Speaker (-) BLACK

Can purchased an adapter kit at Best Buy or Circuit City that is color cordinated with the factory wires for about 12.00. This will go right into the factory plug.

Radio 12v orange + radio harness
Radio Ground black - radio harness
Radio Ignition dk. green + radio harness
Radio Illumination gray (dimmer) + radio harness
Factory Amp Turn-on N/A
Power Antenna N/A
LF Speaker +/- tan - gray +,- radio harness
RF Speaker +/- lt. green - dk. green +,- radio harness
LR Speaker +/- brown - yellow +,- radio harness
RR Speaker +/- dk. blue - lt. blue +,- radio harness
Immobilizer Bypass Module: Required: Yes Type: Passlock 2 Part #: 457G, 555L, or 555T
Notes: The Passlock 2 wire colors are yellow, orange/black, and red/white (not used).

On your vehicle there should be two male plugs from the back of the radio, one black and one gray. The simplest thing to do is get an after market harness but if you really need the wiring,here you go:

12V+ Pink/Yellow
Acc Red/White
Ground Black
Illumination (not really needed) Orange/Brown
Dimmer (also not needed) Black/Light Blue

Speakers:
FL + Dark Green
FL - Brown/Red
FR + Violet
FR - Dark Blue/Red
RL + Brown/Yellow
RL - Brown/Light Blue
RR + Darl Blue/White
RR - Dark Blue/Orange