What’s your first thought when your vehicle light can't work properly after installation? Most of us immediately assume it’s a faulty bulb, right? But what if it’s something else?
Recently, we received a message from a Lasfit customer with a 1996 Ram 2500 who had just installed our T3-3157D LED bulbs. The passenger side worked well, but the driver side... not so much.
“The side markers are awesome too, work and fit great, but my driver side doesn’t blink, just stays solid. Passenger side works perfectly. Diagnosing that as well.”



You can see from the video that the left turn signal light doesn't blink.

After hearing this, Lasfit suggested a little troubleshooting: swap the bulb on the driver’s side with the one on the passenger side. If the bulb works on the other side, you know it’s not the bulb at fault.
He tried it and here’s what happened: the bulb that worked on the passenger side didn’t work on the driver side either! Even swapping back in the original halogen didn’t solve the issue.
Conclusion? It’s not always the bulb. Sometimes, an issue with your vehicle’s wiring or relays might cause one side to malfunction.
“Hey! I actually think the bulbs work great. I switched the sides and the same problem occurred. So I put stock bulbs back in and saw the same issue. So it’s nothing with the product! There’s a deeper problem with a relay, the indicator switch itself or wiring. But your bulbs are awesome.”

This customer even tested the bulbs in his friend’s truck, and they worked perfectly there, confirming the problem wasn’t the bulb.
“I tried the bulbs on a friend's exact same truck and they work perfectly. So definitely not a product issue.”

From this customer’s experience, here’s how you can figure out if it’s a product issue or something with your vehicle:

Lasfit’s Tips:
1. Try swapping the non-working bulb to the other side. If it works, it’s not the bulb.
2. If your friend has the same vehicle, try testing the bulb on their vehicle.
3. Older vehicles are more likely to experience these wiring issues than newer models.

Have you ever had a situation where one side of your vehicle lights can't work properly? How did you go about checking it? Feel free to share your experience and comment below!