Sponsored

Strange Headlight Issue

TGC22

Well-Known Member
First Name
Thomas
Joined
Sep 7, 2019
Threads
4
Messages
47
Reaction score
17
Location
DC
Vehicle(s)
JKU Willys
So recently I've had a strange issue with my passenger headlight. Both headlights are aftermarket LED and have had no issues until now.

Since I bought my truck when I unlock my JT both headlights come on. All of a sudden I noticed that now when I unlock the JT, only the drive side headlight comes on.

Damn, headlight is out. No biggie, off to Amazon and replace the headlight. Well I unlock the JT and same issue... Shit, it must be an electronics fault somewhere. Maybe the wire is damaged.

Here is where it gets strange:

Once the engine is running the headlight lights up no problem... If I remote start it and then unlock the doors, both headlights light up. When I'm driving both light up. It's literally just when the engine if off and I unlock it...

Anyone run into a similar issue?
Sponsored

 

Kevin_D

Well-Known Member
First Name
Kevin
Joined
Oct 18, 2020
Threads
54
Messages
2,382
Reaction score
3,200
Location
Inland Northwest
Vehicle(s)
2021 Sport S, 1971 J4000, a bunch of other stuff
Have you told the truck you’re running LEDs?
LED lamps are much less forgiving of voltage changes than regular light bulbs: a slight voltage drop can cause an LED to not light. Reprogramming for LEDs will help control the voltage presented to the headlights.

Kevin
 

ShadowsPapa

Well-Known Member
First Name
Bill
Joined
Oct 12, 2019
Threads
247
Messages
40,442
Reaction score
53,859
Location
Runnells, Iowa
Vehicle(s)
'25 JTMX, '23 JLU 4xe, '82 SX4, '73 Javelin
Occupation
Retired auto mechanic, frmr gov't ntwrk security admin
Vehicle Showcase
3
All bets are off when you use aftermarket - and from Amazon, they can be anything that will fit.
The factory LEDs have voltage to them actually regulated or controlled. They have a strict set of parameters as far as load, voltages required and used and so on.

Did you use any software or even tazer to tell the truck it has LED headights?

When the engine is running, system voltage is higher - maybe your cheapies don't operate with the low voltages these trucks can have when the engine isn't running?
 

ShadowsPapa

Well-Known Member
First Name
Bill
Joined
Oct 12, 2019
Threads
247
Messages
40,442
Reaction score
53,859
Location
Runnells, Iowa
Vehicle(s)
'25 JTMX, '23 JLU 4xe, '82 SX4, '73 Javelin
Occupation
Retired auto mechanic, frmr gov't ntwrk security admin
Vehicle Showcase
3
Have you told the truck you’re running LEDs?
LED lamps are much less forgiving of voltage changes than regular light bulbs: a slight voltage drop can cause an LED to not light. Reprogramming for LEDs will help control the voltage presented to the headlights.

Kevin
That was a thought I just posted as well. The problem with SOME LEDs is that they may be expecting voltages over 12.4 or whatever and we know these can have lower voltages.
These are "regulated" when running to something around 13.4 or so - but what about when the truck is not running - would it still supply that if it was told it had LED headlights? Or would it be restricted to the lower battery voltage when it's not running? I doubt these increase voltage up to the regulated 13.xx but I suppose it's possible.
 

Kevin_D

Well-Known Member
First Name
Kevin
Joined
Oct 18, 2020
Threads
54
Messages
2,382
Reaction score
3,200
Location
Inland Northwest
Vehicle(s)
2021 Sport S, 1971 J4000, a bunch of other stuff
In JScan there are Voltage Regulation settings for the various lamps ranging from 12-15 volts.
I haven’t experimented to see what effect these settings have or when.
It might be interesting for @TGC22
to try changing this setting, if he has JScan, and see if a higher setting solves his problem.

Kevin
 

Sponsored

OP
OP

TGC22

Well-Known Member
First Name
Thomas
Joined
Sep 7, 2019
Threads
4
Messages
47
Reaction score
17
Location
DC
Vehicle(s)
JKU Willys
Yeah I used JScan to set them as LEDs. It’s weird that they suddenly started doing it after 7 months and it’s only one headlight not both... I’ll play around with the voltage and see if it makes a difference. Thanks for the suggestions.

If it makes any difference they’re full replacements not just the LED drop in bulbs.
 

Kevin_D

Well-Known Member
First Name
Kevin
Joined
Oct 18, 2020
Threads
54
Messages
2,382
Reaction score
3,200
Location
Inland Northwest
Vehicle(s)
2021 Sport S, 1971 J4000, a bunch of other stuff
Yeah I used JScan to set them as LEDs. It’s weird that they suddenly started doing it after 7 months and it’s only one headlight not both... I’ll play around with the voltage and see if it makes a difference. Thanks for the suggestions.

If it makes any difference they’re full replacements not just the LED drop in bulbs.
LEDs can change characteristics as they age. It’s not unexpected for only one lamp to develop an issue.
Let us know what you find.

Kevin
 

Blade1668

Well-Known Member
First Name
Darrell
Joined
Jan 7, 2020
Threads
12
Messages
3,263
Reaction score
3,148
Location
N. AL.
Vehicle(s)
90XJ, 91XJ, 91MJ, 05 LJ, 20 JT
Build Thread
Link
Vehicle Showcase
1
As a noted by Bill and Kevin.. LED's do strange things as age, ect. I've had many burn out in my RV I had replaced most of the 12v bulbs with LED's and had them burn out. I've replaced the fog light bulbs in my JT, strangely the right side one burned out and was replaced by company's warranty. The replacement one has burned out again. It's the first one in line for electric. Reminding me to go replace them again this time I ordered another set of LED's to replace them again.
I'm dang sure I don't know much about this as others, my experience with LED's is that they are better for less power needed (amps-watts) do "burn" brighter but do fail regularly from heat. Not enough heat sink or cooling? The advantages of LED's is they deal with vibrations, shock, lower power draw and longer life. A factor that does "kill" LED's is heat, no cooling inside headlight assembly could be part of the thing to?

Strangely the fog light LED started falling at 7-9 months too.
 
OP
OP

TGC22

Well-Known Member
First Name
Thomas
Joined
Sep 7, 2019
Threads
4
Messages
47
Reaction score
17
Location
DC
Vehicle(s)
JKU Willys
I’m thinking it’s not the LEDs but a setting/issue with the actual Jeep as I did try a brand new set when I thought the headlight was out and the same thing happened.

I’ll play around with JScan and see if anything makes a difference. I do have a volt meter so i’ll see if I can get some readings
 

Jody0Bill

New Member
First Name
Jody
Joined
Aug 8, 2022
Threads
0
Messages
4
Reaction score
1
Location
Boston
Vehicle(s)
20 Gladiator
Make sure the LED bulbs you bought is qualified. There are too many bargains on Amazon these days, and they are all poor quality
 

Sponsored

Joe_G

Well-Known Member
First Name
Joe
Joined
Jun 21, 2022
Threads
8
Messages
125
Reaction score
105
Location
St. Louis
Vehicle(s)
2005 Vette Conv., 03 Harley Heritage Springer
Factory halogen Gladiator. I bought DV8 LED lights (full lights that look just like factory), worked great for 2.5 months (super bright, love them) and my right side light started having this exact problem. It got to the point where the right light would wink on and off while driving though. I got a replacement and same problem. Took out right light, zero voltage to the factory plug light on or off. Put my factory right halogen in and it didn't work either, low beam or high. Took out the left LED to install factory halogens to take it to dealer, figuring I had a wiring problem (all looks good in connector and I tried to follow it back to the fuse block but couldn't see any problems)...now both halogen lights work perfectly.

This is crazy, any ideas?
 
First Name
frank
Joined
Feb 17, 2025
Threads
4
Messages
14
Reaction score
11
Location
NJ
Vehicle(s)
2024 JT
Old thread but yeah. Having same problem in 2024 Sport S. Had halogens and put in DV8 lights. Now the passenger side winks and turns off.
 

Joe_G

Well-Known Member
First Name
Joe
Joined
Jun 21, 2022
Threads
8
Messages
125
Reaction score
105
Location
St. Louis
Vehicle(s)
2005 Vette Conv., 03 Harley Heritage Springer
First Name
frank
Joined
Feb 17, 2025
Threads
4
Messages
14
Reaction score
11
Location
NJ
Vehicle(s)
2024 JT
Thx. I ended up using a bypass cable and JScan and turned them on in the app via OBD. Seem to be working now but we shall see 🤷🏼‍♂️
 

Sweetums

Well-Known Member
Joined
Mar 30, 2023
Threads
28
Messages
2,006
Reaction score
4,314
Location
Utah
Vehicle(s)
'05 LJR, '21 JTDR, '00 VFR800, RSV4, '11 MTS 1200
All bets are off when you use aftermarket - and from Amazon, they can be anything that will fit.
The factory LEDs have voltage to them actually regulated or controlled. They have a strict set of parameters as far as load, voltages required and used and so on.

Did you use any software or even tazer to tell the truck it has LED headights?

When the engine is running, system voltage is higher - maybe your cheapies don't operate with the low voltages these trucks can have when the engine isn't running?
This is the right answer. Even if you buy name brand lights from Amazon, there's a decent chance they are counterfeit. Amazon is basically Temu to Alibaba these days with all the other sellers using the Amazon platform.
Sponsored

 
 







Top