Yes, the LED's require a bias resistor, it is under the shrink tubing. I set the bias (resistor's value) to determine the brightness of the LED. On the dash you can see the red LED is brighter than the blue one, the red one is my parking brake warning light intentionally bright so I take the brake off, lol. Normally I set them on the dim side as they are just indicators and I don't want them distracting me.
I use a resistor substitution box to dial in their brightness, then install the desired resistor to set the bias. But you can also do it as outlined below if you do not have a substitution box.

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