license plate light comes on when any door opens? post led install

this is not normal, have you done any mods besides lite bulbs?

 

An assumption would be you have already replaced the little 12V battery at some point. The first sign of a weak battery is electrical gremlins. I would check 12V health anyway, as you might have a parasitic drain somewhere. Could be something electrical or electronic due to a circuit expecting to see regular bulb filament resistance and instead seeing a forward biased diode. Prius is funny like that.

 

Something cross-connected?

I never tire of recollecting the time I switched the windshield washer and left turn light connectors: all was fine till I had to turn left...

 

I replaced all of my lights with LEDs in my 2008 with smart key system. When I walk next to the car, the amber front side markers and the red tail lights will light up very dim, not enough power to light up standard bulbs, but enough to make LEDs emit a very faint glow... If I hit the lock button on the remote, they will turn off. This behavior began when I put LEDs in. I believe that it is normal for the Prius to send some tiny current to these bulbs when you open the doors or are close to the car if SKS equipped.

 

My 2009 Prius does the same thing but it's my brake lights. Whenever my interior dome light would be on when set to 'Door' my brake lights light up dimly (but not my licence plate lights). Similarly, I have all my interior, parking, brake, reverse, and licence plate lights replaced with LEDs (still have stock turn signal and headlights). My battery was replaced this December, so I don't think it's related to a low battery. Pushing the lock button on my FOB turns off these lights just light as it does the door lights, so I have no problem with this behavior.

I do know that some LED replacement lights have DC to DC converters built into them. For this reason you'll sometimes see things like "Operating Voltage: 6-24V" on their specifications. My best guess is that the Prius' ECU(s) are sending a trickle of current to the LEDs and when this gets stepped up by the DC-DC converter in the LED light, it's enough to dimly light it up. I think it's basically a "hardware bug" and nothing to be worried about.

 

No clue how to solve it, but I would guess there is a small leak somewhere: the switch in the door normally opens (or closes so you will) a path between the interior lights and ground. LED's can function with the tiniest of current (that might also pass through any other component, even e.g. a coil of a relay), so as mentioned above, what would never even dimly light up a normal filament bulb, will be enough to make an LED 'glow'.

I have a set of Ikea LED lights above my bed. There is a minute current going through the plastic (!!!) of the ON-OFF switch that lights a few of the 50 LEDs enough to be visible when all other lightsources are off. [unrelated to your problem] I have yet to test if the switching powersupply that came with the lights has any influence in this[/unrelated to your problem]. I opened up the switch and there is no visible other road the electrons can travel than through the plastic. As soon as I remove the metal parts that make up the switch from the plastic, the LED's go dark.
Problem for me is that I could not properly measure my issue (iirc the resistance I measured was infinite, so they shouldn't light up!) and I am somewhat afraid you will have the same problem.

 

nice to hear from you r-p!

 

I don't know if it's the same problem, but a friend had a similar problem in an old VW after he changed his tail lights. One of the tail lights was shorting and causing weird lighting issues. We replaced the lights and the issues went away. Have you tried replacing the new LED's one at a time with the old bulbs?

 

R-P it sounds like the issue with your bed lights is related to a capacitance or an inductance problem - Either there is some circuitry of wires close enough together that they're behaving like a poor transformer and transmitting a bit of current, or there are two metal plates that are close enough to behave like a capacitor and transmitting voltage (capacitors behave like a short with high enough frequency AC signals, also some materials which are not highly conductive can still act like capacitors, the plastic casing could behave this way). You won't be able to find this by measuring resistance.

In the car we shouldn't be seeing this problem however as it uses DC and not AC.