2005 tl. Had a front 7443 parking /turn bulb go out. I ordered these up 2pcs Big Promotion T20 W21/5W 7443 13 SMD 5050 LED Pure White Car Auto Light Source Brake Parking Reverse Lamp Bulb DC12V-in Light Source from Automobiles & Motorcycles on Aliexpress.com | Alibaba Group

Even though they are listed as a 7443 and have 4 leads on them. They wont come on when the headlights are turned on, they only blink when i use the signal. Is that the nature of LEDs? Is that why everyone uses switchbacks? I am confused, i thought all 7443 bulbs are "dual filament or dual density" Thanks.

 

Have you tried flipping the bulb?

 

Yes, I also ordered a second set of 7443, of a different design, for a buddy. Those refuse to work as well. I'm guessing it is a design error. They work just fine in a single filament application, 7440, but no luck as a 7443 as advertised. weird

Are our 7443 harness/plugs standard or CK style?

 

one thing you could try doing is lifting up the metal leads/contact on the end of the bulb, perhaps they are not making contact inside the connector? I haven't had any issues using the 7443 LED on mine

also just checked the link - am i reading that right? $0.80 for the bulb - that right there could be some of the problem, cheap, too cheap lol - i have switchbacks from Diode Dynamics...not one issue.