Led tail light issue

[tommy2704]

Originally Posted by andrewwynn

You have used a couple confusing terms that don't match standards.

You have been calling the "run/ning" light circuit the "light" circuit they are all light circuits.

The run circuit runs at full voltage and is incompatle with your lighting. Wire a 24 Ω resistor from that wire to ground.

You may still get an error because the brake lamps also don't pull enough power in which case you would need to wire a lower resistance resistor in parallel to the BRAKE circuit (which is actually run/brake circuit. ).

I would need to know what amount of current the circuit pulls when lighting both top and bottom to know the correct resistance to emulate the 21w filament but people usually use 6 Ω. It likely needs closer to 8-10 Ω but only trial and error will determine what level will prevent the error.

The problem is two fold:

1) you don't have run wire connected at all the car correctly identifies this as a blown filament.

2) the brake circuit has too low of resistance even when doubting up the lamps, so it will likely see this as a failing filament.

If you know the wattage of the LEDs or can measure the current going to get fixture when the brakes are applied I can do the math to tell you the proper resistor.

A 6 Ω resistor at 12v is 24w! That's similar to a small soldering iron so it needs to be a special metal resistor and should be touching metal to pull the heat out.

If you only need 10 Ω, the power drops from 24w to 12w or half so it's worth figuring out what is actually needed.

With any luck simply doubling up the lamps (which you did) will trick the car into thinking the lamp isn't blown.

ok well firstly thanks for the proper reply. sorry for the confusion.
i gather you mean the run circuit is the main back lights?
if they are incompatible then why are they in the connector? (never had a set of these before)
They are the ones, when connected, that are as bright as the brake lights so i guess thats where the full voltage comes in.
So why cant i put a resistor in that wire to lower the full voltage??

Also, the brake circuit (run/brake circuit) is absolutely fine and works perfectly without any resistors. Doubled up as you said. No warnings about brakes. The ONLY warning i get is because the main run circuit is not connected to anything.
Thats how ive got it wired at the moment and all lights/ brakes etc are working perfectly.
What i needed to know was about putting a resistor in the main run circuit so that i could connect the light fitting properly without any alarms going off.
hope i explained this right.