Originally Posted By: Johnny248
Usually not. Most vehicles will require a resistor or they will hyper flash.
The "no code" thing is usually more for the can-bus system. Many vehicles will show a bulb out warning if you install LED's. The can-bus LEDs prevent that. Also, some vehicles have issues with the dimming interior lights if led's are installed. In those cases, the can-bus LED's take care of that problem also.
I have installed many, many, many led lights in vehicles. As far as turn signals go, you pretty much will always have to install a 15w resistor or similar inline with the LED in order for them to flash properly. Some vehicles you can get away with replacing your turn signal flasher unit with an electronic load adjusting unit instead of a thermal flasher. Most cars will allow you to change things such as running lamps, interior bulbs, incense plate, reverse lights, etc without any issues. Again, the can-bus bulbs are a better choice because it takes the guessing out of it if you need one or not. The kits I've seen at Walmart are advertised as Dome Lamp kits had and three different LED's I believe.
There are a few LED lights that will work without resistors, but these things usually cost in the $25-100 each range. Much less expensive to wire some resistors with the less expensive bulbs.
One other thing I should point out. If you are using something like a 3157 dual filament turn signal bulb, cheaper LED's don't do a great job of having a distinguished low and high output. It makes it harder to see when the turn signal is activated while the running lights are turned on in the car. Also, some applications make it difficult to see the LED turn signals in the day also depending out how the lamp is designed.
If you do want to add the LED turn signals, simply get some 15w resistors and tap them into the turn signal bulb wires. I have multiple vehicles running fine with them like that. It isn't a lot of work.
I agree with your comments. I replaced my #921 reverse bulbs with "super bright" LED bulbs. Looking at them they were very bright, but the light on the ground was less than the OEM bulbs. I believe this was caused by the LEDs not being at the reflector focal point. I put the OEMs back in. My wife's comment was, " Looks like Toyota knew what they were doing". Replacing the trunk light OEM bulb with a LED did make a big difference in visibility.