LED Install Problem (Tails)

[CTScott]

The 7443 bulbs have 4 contacts. Make sure you didn't bend one of the socket contacts when you were switching back and forth.

The turn signals need the replacement flasher module or a load resistor because the standard flasher relies on the resistance of the bulb filament for its timing circuit.

The Yaris doesn't have dead bulb detection, so load resistors are not necessary for anything except the turns.

The stop/tail bulb has two filaments. If your replacement LEDs were not true 7443 bulb replacements, then they may have been jumping the stop light circuit over to the tail light circuit and hence causing the headlight indicator to illuminate (and the cluster to dim) when you stepped on the brake pedal.