What is the problem when it says left rear position light failure

Here is a free wire diagram color coded for a 2000 Chevy Impala LS:
Battery Constant 12v+ Positive Wire (Yellow): The constant 12V+ wire is yellow.
Starter Positive Wire (Purple): The starter wire is purple.
Ignition Positive Wire (Red): The ignition wire is red.
Second Ignition Positive Wire (Pink/White): The second ignition wire is pink/white.
Accessory Positive Wire (Orange): The accessory wire is orange.
Power Antenna Turn On (Blue): The power antenna wire is blue.
Amplifier Turn On (Blue/White): The amplifier wire is blue/white.
Left Front Speaker Positive Wire (+): The left front speaker wire is tan.
Left Front Speaker Negative Wire (-): The left front speaker wire is gray.
Right Front Speaker Positive Wire (+): The right front speaker wire is light green.
Right Front Speaker Negative Wire (-): The right front speaker wire is dark green.
Left Rear Speaker Positive Wire (+): The left rear speaker wire is brown.
Left Rear Speaker Negative Wire (-): The left rear speaker wire is yellow.
Right Rear Speaker Positive Wire (+): The right rear speaker wire is dark blue.
Right Rear Speaker Negative Wire (-): The right rear speaker wire is light blue.

Car Radio Battery Constant 12v+ Wire: Red/White
Car Radio Accessory Switched 12v+ Wire: Orange (Data Bus Wire)
Car Radio Ground Wire: Black/White
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

Radio Battery Constant 12v+ Wire: Light Green
Car Radio Accessory Switched 12v+ Wire: Yellow/Black
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Light Blue/Red
Car Stereo Amp Trigger Wire: Blue
Car Audio Front Speakers Location: Doors
Left Front Speaker Positive Wire (+): Orange/Light Green
Left Front Speaker Negative Wire (-): Light Blue/White
Right Front Speaker Positive Wire (+): Dark Green/Orange
Right Front Speaker Negative Wire (-): White/Light Green
Car Audio Rear Speakers Location: Rear Doors
Left Rear Speaker Positive Wire (+): Gray/Light Blue
Left Rear Speaker Negative Wire (-): Tan/Yellow
Right Rear Speaker Positive Wire (+): Orange/Red
Right Rear Speaker Negative Wire (-): Brown/Pink

Windstar Car Stereo Radio Wiring Diagram - All years
Car Radio Constant 12v+ Wire: Green/Violet Car Radio Switched 12v+ Wire: Yellow/Black Car Radio Ground Wire: Black/Light Green Car Radio Illumination Wire: Green
Left Front Speaker Positive Wire (+): Orange/Light Green Left Front Speaker Negative Wire (-): Light Blue/White Right Front Speaker Positive Wire (+): White/Light Green Right Front Speaker Negative Wire (-): Dark Green/Orange
Left Rear Speaker Positive Wire (+): Light Brown/White Left Rear Speaker Negative Wire (-): Light Brown/Yellow Right Rear Speaker Positive Wire (+): Light Brown/Green Right Rear Speaker Negative Wire (-): Brown/Pink

Speakers
1995-1998: 5" x 7" Front door and side panel 1999-2003: 6" x 8" Front and rear door

2000 Ford Crown Victoria Car Radio Stereo Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Violet/Light Blue
Car Radio Accessory Switched 12v+ Wire: Yellow/Black
Car Radio Ground Wire: Black/Light Green
Car Radio Illumination Wire: Light Blue/Red
Car Stereo Antenna Trigger: Blue
Left Front Speaker Positive Wire (+): Orange/Light Green
Left Front Speaker Negative Wire (-): Light Blue/White
Right Front Speaker Positive Wire (+): White/Light Green
Right Front Speaker Negative Wire (-): Dark Green/Orange
Left Rear Speaker Positive Wire (+): Gray/Light Blue
Left Rear Speaker Negative Wire (-): Tan/Yellow
Right Rear Speaker Positive Wire (+): Orange/Red
Right Rear Speaker Negative Wire (-): Brown/Pink

1990 to 2008 Chevrolet Silverado C1500 Car Stereo Wiring Guide
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

Good luck and this should help

Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

Constant 12V+ Brown/White
Switched 12V+ Orange
Ground Black/Light Green
Illumination Pink/Black
Dimmer Pink
Front Speakers 5" x 7" Doors
Left Front (+) Gray/Blue
Left Front (-) Yellow/Blue
Right Front (+) Blue
Right Front (-) Yellow
Rear Speakers 5" x 7" Side Panels

Left Rear (+) Blue/White
Left Rear (-) Blue/White
Right Rear (+) Blue/Black
Right Rear (-) Red/Blue

Thanks for using FixYa - a FixYa rating is appreciated for answering your FREE question.

1998 Chevrolet Blazer S-Series Stereo Wiring Constant 12V+ Orange Switched 12V+ Yellow Ground Black Illumination Gray Dimmer Brown Antenna Right Front Front Speakers 6 1/2" Doors Left Front (+) Tan Left Front (-) Gray Right Front (+) Light Green Right Front (-) Dark Green Rear Speakers 6 1/2" Rear Doors Left Rear (+) Brown Left Rear (-) Yellow Right Rear (+) Dark Blue Right Rear (-) Light Blue