Which Tail Light Bulb to Replace

[PyrPatriot]

I suspect I have a single bulb that is out. When I unlock my Jeep, there is the usual flash of the tail lights, and usually they stay on. A few days ago I noticed one does not stay on. Both lights work while applying the breaks and while backing up. I do not know for certain how they appear during usual driving with the lights turned on, but I think they are both appearing normal. Based on parts diagrams I only see 2 bulbs: a Bulb 7440/W21W and Bulb 3157K. I do not have LED tail lights.

As I want to avoid taking the tail light assembly out, looking at the bulbs, and then running to the store in another vehicle to see if they have the right bulb, I wanted to ask here first. Which bulb do you think is bad? Or, is it an electrical issue? My aux battery is likely dead and main needs replacing soon based on age (3y almost) and mileage (61k miles).


Eta: 7443 and 421 are the bulbs. Dont know what the side bulb/turn signal is yet. None of the bulbs ended up being out

Sponsored

 

[JTR178]

Replace the 3157. It's dual filament and sounds like only one of them has burned out.

 

[snowbear]

Or get one of each.

 

[jeepdan]

I just went through this with my 2020 Overland.

Bulbs 3157 and the 7440 did not fit!

I could not make out the numbers stamped on the original bulb.
After much aggravation, I found that a 7443 fits the tail lamp socket.

 

[PyrPatriot]

I just went through this with my 2020 Overland.

Bulbs 3157 and the 7440 did not fit!

I could not make out the numbers stamped on the original bulb.
After much aggravation, I found that a 7443 fits the tail lamp socket.

Just to be clear, non LED package right?

 

[jeepdan]

Just to be clear, non LED package right?

Correct, normal incandescent bulb.

 

[PyrPatriot]

None of the bulbs were out. The brake light socket you can take out and it can light up. The tail light however will not light up if the socket insert is out. I tried the other "good" tail light and it would not light up until I put the insert back in. Tried the "bad" bulb in the other light and it worked.

Tail light ended up being a 921 bulb.

Replaced both bulbs in both sides

 

[JT_in_FL]

I confirm on non-LED 2020 Gladiator Sport S. 7443 fit.

I tried the 3157 and it just fell out.

Id say pull the bulb and verify before buying anything. the 3157 has a much thinner base.

Sponsored