Modern cars can have sensitive electrical circuits. Replacing an old filament lamp with an LED, can have an affect on the circuit (a change in the load). It may cause your indicators (turn signals) to flash faster, often called hyper flashing. The CAN bus system (the vehicle electronics) can also think there is a bulb failure.
To get around this issue, you have to add a load resistor in parallel with the LED light. I.e. The load resistor goes across the light bulb connections, between the LED’s supply and ground.
Basically, you make the LED light have the same load as the original filament light bulb, (by adding a load resistor). A load resistor is required for each LED light bulb in the turn signal circuit, (2 x LED’s will need 2x load resistors).
The video above, explains how to Install a Load Resistor for LED Lights (it provides the theory, wiring diagrams, etc).
Can be found on this page: How to Install Load Resistors for LED Turn Signal Lights: (Opens in a new window / tab)