Is there a fuse for the fog lights?
- Thread starter Georgia_Dirt
- Start date
I can‘t find the fuse in the owners manual for the headlamps, I just see headlamp wash and wash relay.
The computer monitors the current on the circuit and automaticaly shuts the system off if it senses something outside of the OEM parameters. No fuse for fogs.
WestCoastDan
JK Enthusiast
Reviving this to see if there are any recommendations on the best way to use the factory wiring for aftermarket lamps that will not illuminate when connected to the factory harness.
I know the lights work as I have tested them individually from a stand alone battery.
I measure voltage at the factory connector w/ the fog light switch activated, but when I connect the aftermarket lights they will not illuminate.
I was thinking that adding a relay might work, but if the ECU is monitoring for current draw, I'm not convinced that the coil of the relay would be enough to 'trick' the system into working w/ my new lights.
Is this possibly something that Jscan can help resolve?
I know the lights work as I have tested them individually from a stand alone battery.
I measure voltage at the factory connector w/ the fog light switch activated, but when I connect the aftermarket lights they will not illuminate.
I was thinking that adding a relay might work, but if the ECU is monitoring for current draw, I'm not convinced that the coil of the relay would be enough to 'trick' the system into working w/ my new lights.
Is this possibly something that Jscan can help resolve?
WestCoastDan
JK Enthusiast
You are definitely correct regarding polarity requirements for LEDs, but that is not the problem here.
As I mentioned above, I tested the lights w/ an external battery. This confirmed functionality as well as wire color/polarity. In this case, the red wire for the lights is indeed the hot leg (I've seen cases where the factory has mistakenly reversed the wire connections internally).
I was able to locate some settings in Jscan, but they did not seem to change the result; no light output when the fog light switch (on the headlight stick) is engaged.
Output at the factory plugs is 12VDC and the polarity there is also correct w/ wire color.
BTW, I happen to be the Engineering Manager for an LED lighting company (non-automotive).
I'm fairly certain at this point that the issue is related to a current sensing parameter within the ECU and an incompatibility with this particular brand of lighting. I can't think of any other explanation.
I wasn't sure if you had confirmed the wire polarity, because it's easy to assume the factory did it right.
No other ideas offhand, but if I think of anything...
It is an odd thing though. I've got LEDs plugged into the factory fog light circuit on both Jeeps and had no problem.
No other ideas offhand, but if I think of anything...
It is an odd thing though. I've got LEDs plugged into the factory fog light circuit on both Jeeps and had no problem.
WestCoastDan
JK Enthusiast
I checked again w/ Jscan and found (2) codes - likely from having the switch mistakenly activated w/o any lights connected.
B16FD - front right fog lamp control circuit high & B16F8 - front left fog lamp control circuit low.
I cleared the codes, reset the ECU and now I only have B16F8...
I've decided to postpone additional effort on this for now as I have a ton of other stuff to do before heading out to the mountains for the weekend.
It'll have to wait.
macleanflood
JK Enthusiast
WestCoastDan
JK Enthusiast
I used a wiring harness for like a light bar setup for my led fog lights. Instead of using the switch that came with the kit, I took those wires and spliced them into my factory wiring. This way when you want to turn the fog lights on you can still use the factory fog light switch.
WestCoastDan
JK Enthusiast
That was definitely the plan. I hate cheap aftermarket switches, so I really want the factory fog light switch to work for these, but I may have to change that plan due to “ECU interference”… damned thing is too smart.
I had somewhat the same problem. My led lights would flicker like strobe lights then turn off and not come back on. I would get a code but don't remember the code anymore. After I used the wires harness I haven't had a single problem since.
I was thinking of your fog light issue . Your new bumper has 4 fog lights .
Are you trying to run all four fog lights off the factory switch ?
Try hooking up 2 and see if that works. If 2 works than maybe 4 is too much of a load and can bus doesnt like it .
I have 2 led fogs in my bumper and no issues whatsoever so was surprised to read your having some problems .
One option is 2 connected to fog light switch and the other 2 to separate switch .
You mentioned in another thread using factory style switch fir the light bar .
Use another one of those switches for 2 fogs .
I think he is using LED lights. I have 4 of those connected to the OEM fog light switch on our '11 with no problem. But it's worth a try...
WestCoastDan
JK Enthusiast
Current configuration will not power even a single light… I suspect the load is too LOW, thus the ECU reacts as if the bulb is burned out (reducing current to 0)…
You could test that theory by adding a few more lights to the circuit.