JK Headlights not getting enough voltage
10-27-2015, 01:55 PM
#11
Super Moderator
Not sure on that. The way to test the presence of the pulse is like one of the others posted.
Key On / Engine Off - should be full 12V
Key On / Engine On - if pulse then you'll get a low voltage on your meter / if not pulse then you'll get a full 12V
Key On / Engine Off - should be full 12V
Key On / Engine On - if pulse then you'll get a low voltage on your meter / if not pulse then you'll get a full 12V
10-27-2015, 02:21 PM
#12
JK Jedi Master
The 2008 service manual says the TIPM sends PWM voltage to the headlights. When it describes the fog lights, it say the TIPM sends battery voltage to the fog lights.
Guess I'll have to go out and put a duty cycle meter on the fog light wires.
Guess I'll have to go out and put a duty cycle meter on the fog light wires.
Last edited by ronjenx; 10-27-2015 at 02:27 PM.
10-27-2015, 02:53 PM
#13
JK Junkie
I've read countless threads on people having issues when replacing the fogs. I think the meter will show that they are PWM. Search "fog flickering".
Last edited by 14Sport; 10-27-2015 at 02:56 PM.
10-28-2015, 11:07 AM
#14
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Problem solved
Problem solved! 
When the Jeep was off, the LED lights worked fine. As soon as I turned the Jeep on, they flashed a couple of times, then went out. It seemed like the PWM was detecting if there was a light on the end, didn't detect one and then shut off and turned power off to the line.
I added resistors to each headlight harness to 'trick' it into thinking there was a bulb on the end instead of the LEDs. Now, when I turn the Jeep on they no longer flash. In addition, they have stayed on ever since without flickering or anything. Seems like problem solved. Only problem, those resistors are really *$%&_* hot. I need to find a place to mount them so they don't melt anything under the hood.
When the Jeep was off, the LED lights worked fine. As soon as I turned the Jeep on, they flashed a couple of times, then went out. It seemed like the PWM was detecting if there was a light on the end, didn't detect one and then shut off and turned power off to the line.
I added resistors to each headlight harness to 'trick' it into thinking there was a bulb on the end instead of the LEDs. Now, when I turn the Jeep on they no longer flash. In addition, they have stayed on ever since without flickering or anything. Seems like problem solved. Only problem, those resistors are really *$%&_* hot. I need to find a place to mount them so they don't melt anything under the hood.
10-28-2015, 11:17 AM
#15
Super Moderator
Problem solved!
When the Jeep was off, the LED lights worked fine. As soon as I turned the Jeep on, they flashed a couple of times, then went out. It seemed like the PWM was detecting if there was a light on the end, didn't detect one and then shut off and turned power off to the line.
I added resistors to each headlight harness to 'trick' it into thinking there was a bulb on the end instead of the LEDs. Now, when I turn the Jeep on they no longer flash. In addition, they have stayed on ever since without flickering or anything. Seems like problem solved. Only problem, those resistors are really *$%&_* hot. I need to find a place to mount them so they don't melt anything under the hood.
When the Jeep was off, the LED lights worked fine. As soon as I turned the Jeep on, they flashed a couple of times, then went out. It seemed like the PWM was detecting if there was a light on the end, didn't detect one and then shut off and turned power off to the line.
I added resistors to each headlight harness to 'trick' it into thinking there was a bulb on the end instead of the LEDs. Now, when I turn the Jeep on they no longer flash. In addition, they have stayed on ever since without flickering or anything. Seems like problem solved. Only problem, those resistors are really *$%&_* hot. I need to find a place to mount them so they don't melt anything under the hood.
10-28-2015, 11:48 AM
#16
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Good deal. So that's a drawback of that SMS box perhaps. The harness I use plugs into one of the H13 headlamp plugs and sends that signal to the capacitors and then to the relays which activate the circuit that ties into the H4 plugs and uses power from the battery (with a fuse) directly.
Did you build your harness yourself or buy it? If you bought it, can you send me a link to what you used?
10-28-2015, 01:09 PM
#17
Super Moderator
Actually....this is bypassing that SMS box altogether. I think I may just take that box out actually since its working without it. No need to risk screwing things up again.
Did you build your harness yourself or buy it? If you bought it, can you send me a link to what you used?
Did you build your harness yourself or buy it? If you bought it, can you send me a link to what you used?
I built my harness. I use a Bussman fuse panel to run my fuses and relays. The only items not in the Bussman is the diodes and capacitor I used to get the flicker out.
10-28-2015, 04:19 PM
#18
JK Jedi Master
