rear left side light not working
Check for blown fuses and a loose connection to the light in the boot.
Where exactly is this light?
If you look in the boot of the car you should see a cover or a opening in each corner of the boot and behind them you will have access to the lights.
also check for broken wires or wire coating as even the slightest crack can cause a bulb to not work. also, make sure not to touch the bulbs
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