DRLs no longer running
Thread Starter
JK Newbie
Joined: Jun 2025
Posts: 2
Likes: 0
From: So Cal
DRLs no longer running
I have a 2016 Jeep Wrangler JKU. In 2019, I installed GTR LEDs in the fog/driving lights, then configured the system to have the DRLs come on when in gear.
Last month one of the lights stopped functioning. I assumed the GTR bulb had failed. I purchased a different set of LED bulbs and today began the bulb replacement.
I started up my Jeep, set the E-brake, and put it into gear, to confirm the failed bulb. Now both bulbs are not working.
On the assumption that both GTR bulbs had failed, I replaced both bulbs. Neither of the bulbs worked. That points to a wiring or computer problem.
I went about checking for a blown fuse only to discover that the JKU has no fuse for the fog/driving lights. The computer monitors the bulb function and shuts down if needed.
While surfing here at JK-Forum, I found a trick to hold the odometer reset button while turning the key to ON. This apparently does some diagnostics and some form of reset.
Alas no joy. Still no driving lights while in gear.
I manually turned on the driving lights from the column switch. Both lights illuminate. This confirms continuity from the power source to the bulbs.
I am now assuming there is a configuration or computer error that disabled one, then both driving lights to auto run while in gear. I need no dig out my scan tool and check the setting and for any error codes.
While I am doing that, I'd appreciate any input regarding source of the problem and any possible fixes.
Thank you for your assistance.
Last month one of the lights stopped functioning. I assumed the GTR bulb had failed. I purchased a different set of LED bulbs and today began the bulb replacement.
I started up my Jeep, set the E-brake, and put it into gear, to confirm the failed bulb. Now both bulbs are not working.
On the assumption that both GTR bulbs had failed, I replaced both bulbs. Neither of the bulbs worked. That points to a wiring or computer problem.
I went about checking for a blown fuse only to discover that the JKU has no fuse for the fog/driving lights. The computer monitors the bulb function and shuts down if needed.
While surfing here at JK-Forum, I found a trick to hold the odometer reset button while turning the key to ON. This apparently does some diagnostics and some form of reset.
Alas no joy. Still no driving lights while in gear.
I manually turned on the driving lights from the column switch. Both lights illuminate. This confirms continuity from the power source to the bulbs.
I am now assuming there is a configuration or computer error that disabled one, then both driving lights to auto run while in gear. I need no dig out my scan tool and check the setting and for any error codes.
While I am doing that, I'd appreciate any input regarding source of the problem and any possible fixes.
Thank you for your assistance.
Thread Starter
JK Newbie
Joined: Jun 2025
Posts: 2
Likes: 0
From: So Cal
Got it sorted out.
I found my FlashCal and plugged it in. It showed the fog lights selected as DRLs. So the configuration is good.
I did a system scan for codes. It showed 6 codes as High for: left high beam, left low beam, right high beam, right low beam, left fog light, right fog light.
That could explain the DRLs not engaging. I reset the codes. No joy.
All codes reset, but left high and low beam, and still no DRLs.
I did some reading on the DRL function. With an automatic transmission the DRLs engaged when the Jeep is out of Park. With a manual, the lights engage when the E-brake is released.
On a hunch, I released the E-brake and used the foot brake. The DRLs fired right up when out of park.
When I originally installed LEDs in the fog lights, I did the testing by starting the Jeep, setting the E-brake and putting it in drive. I was able to get out and check the DRLs while the E-brake held the Jeep in place.
I thought the Jeep needed to be in gear to engage the DRLs. It just needs to be out of park. I can now self-test by parking on level ground, chocking a wheel, start Jeep, put in Neutral. Check DRLs. No need for a spotter.
Inexplicably my automatic transmission Jeep now functions as a manual transmission Jeep, with regards to DRL operation. E-brake must be disengaged for DRLs to function.
The DRLs now function properly.
I’m still scratching my head why the Jeep threw 6 lighting codes and why it is still throwing codes for the left high/low beam, even If I never turned on the headlights.
I found my FlashCal and plugged it in. It showed the fog lights selected as DRLs. So the configuration is good.
I did a system scan for codes. It showed 6 codes as High for: left high beam, left low beam, right high beam, right low beam, left fog light, right fog light.
That could explain the DRLs not engaging. I reset the codes. No joy.
All codes reset, but left high and low beam, and still no DRLs.
I did some reading on the DRL function. With an automatic transmission the DRLs engaged when the Jeep is out of Park. With a manual, the lights engage when the E-brake is released.
On a hunch, I released the E-brake and used the foot brake. The DRLs fired right up when out of park.
When I originally installed LEDs in the fog lights, I did the testing by starting the Jeep, setting the E-brake and putting it in drive. I was able to get out and check the DRLs while the E-brake held the Jeep in place.
I thought the Jeep needed to be in gear to engage the DRLs. It just needs to be out of park. I can now self-test by parking on level ground, chocking a wheel, start Jeep, put in Neutral. Check DRLs. No need for a spotter.
Inexplicably my automatic transmission Jeep now functions as a manual transmission Jeep, with regards to DRL operation. E-brake must be disengaged for DRLs to function.
The DRLs now function properly.
I’m still scratching my head why the Jeep threw 6 lighting codes and why it is still throwing codes for the left high/low beam, even If I never turned on the headlights.