Fog light stopped working

[Enkriss]

I have a 2016 1500. I replaced all the bulbs about a year ago with OPT7 LED Fluxbeams. All was fine and well until recently.

My fog lights stopped working. I checked the harness connectors at the fog lights and I am not getting any power. I checked several fuses F10 being one of them. They all seem perfectly fine. When I push the fog light button the green (fog) light comes on in the instrument cluster. I do not hear any relays clicking when pressing the fog light switch.

Is there a relay for the fogs in these trucks? None of the descriptions of the Kxx relays say anything about fog lights. Is the fog light relay somewhere else in the truck and not in the under hood fuse box? Could it be the headlight/dimmer switch? Does anyone have a wiring diagram for the fog light circuit?

 

[crash68]

Probably the cheap CANbus adapters that com with those Opt7 fogs. I had to replace mine, used the ones from Diode Dynamics.
Turn the ignition ON (fog lights do not come on in Acc) but don't start the truck and check the fog lights. If they work it is the probably the CANbus adapters. If they don't your problem is elsewhere, check for power. Maybe try putting the stock bulbs back in to troubleshoot.a

 

[Enkriss]

Probably the cheap CANbus adapters that com with those Opt7 fogs. I had to replace mine, used the ones from Diode Dynamics.
Turn the ignition ON (fog lights do not come on in Acc) but don't start the truck and check the fog lights. If they work it is the probably the CANbus adapters. If they don't your problem is elsewhere, check for power. Maybe try putting the stock bulbs back in to troubleshoot.a

I unplugged both at the factory harness before all the opt7 wiring and checked for power. Nothing.

 

[chopperman1]

Perhaps a stupid thought but are your high beams on? There is a fog light interlock that shuts them off with high's. Try flashing your high's a few times.

 

[Enkriss]

Perhaps a stupid thought but are your high beams on? There is a fog light interlock that shuts them off with high's. Try flashing your high's a few times.

The fog light indicator comes on in the dash so the switch seems to be on for them to turn on.

I just went and flipped the highs off and on a bunch. The fogs still do not work.

 

[Enkriss]

Looking at my fuse box. None of the descriptions for the relays say anything about fog lights.

Do any of these operate the fog lights?

 

[Enkriss]

Does anyone know the location of the fog lamp relay in a 4th gen RAM 1500?

 

[alpinegreenneon]

There is no separate replaceable fuse or relay for the fog lights as far as I see. Fuse 10 is for all the exterior lighting and the BCM ultimately controls exterior lighting. There may be a soldered in relay on the BCM. The led you installed may have damaged something in the BCM. Have you tried replacing the original bulbs?

From the FSM:
FRONT FOG LAMPS
Vehicles equipped with optional front fog lamps include a front fog lamp switch integral to the headlamp switch on the instrument panel. The front fog lamps have a path to ground at all times through their connection to the headlamp and dash wire harness and a takeout with an eyelet terminal that is secured to the body sheet metal. The BCM monitors a hard wired multiplex input from the headlamp switch to determine whether the fog lamps are selected.

When the BCM input from the headlamp switch indicates the fog lamps are selected, it controls front fog lamp operation by providing a battery voltage output to the fog lamps through the right and left front fog lamp control circuits. The BCM also sends the appropriate electronic messages to the Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC) to illuminate or extinguish the front fog lamp indicator. The BCM will automatically de-energize the front fog lamps any time the headlamp high beams are selected, except on vehicles manufactured for certain export markets.

The BCM also provides a battery saver (load shedding) feature for the front fog lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position, if there is a charging system failure, or if the electrical system voltage falls below about 11.75 volts for more than about 30 seconds.

 

[Enkriss]

Thanks for help.

Is there a way to test the BCM or headlight switch to narrow it down?

If it was something wrong with the BCM wouldn’t I get some kind of light or message in the dash control panel?

 

[chopperman1]

Did you try to put the stock bulbs back in and try it? Could be something in the CANBUS system not turning on the voltage until a specific condition is met. Next option... can you put the stock bulbs back in and bring it to the dealer for warranty work?

 

[Enkriss]

Low beam went out now. I am going throw all the OEM stuff in this weekend and bring it to the dealer.

 

[Enkriss]

Hmmm....

I put the OEM fog light bulbs in. Didn’t work...

Disconnected the battery for a bit and reconnected it. Fog lights came back on.

 

[tim Fida]

Hello All,
I have a 1995 Dodge Ram 1500 5.9L. Fog Lamp switch won't stay depressed. When I press it the indicator light comes on but the button won't stay in.
I have replaced Fog lamp bulbs and headlight bulbs. The truck doesn't have a Fog lamp relay, only a fuse which is good. Any ideas?

 

[Racked363]

Tim fida, I am having same issue with foglamp switch not staying depressed. Did you ever figure out the reason?