JK Headlights not getting enough voltage
 

I have an 07 Rubi. Recently bought LED headlights and found an issue with my Jeep. When I turn the headlights on with the Jeep off, they are getting the correct 12v. About a minute after I turn the Jeep on, the voltage goes down to 0 then fluctuates to about 2.5 and down to 0 (coming out of the original Jeep H13 plug). I have tried the SMS wiring harness but it still uses the original Jeep harness to trigger the relays, so that doesn't work since it needs about 8 volts per Ray at rallylights.com. I understand it is probably something wrong with the PWM in the TIPM. Instead of spending $250-$300 on a new TIPM (which has no other issues than the headlights), is there a way I can wire the original Jeep H13 harness to get the extra voltage to trigger the relays in the SMS harness? Can I somehow use the parking brake wiring? Those seem to work just fine.

note - I did test the battery. Jeep off with headlights on battery reads at 12.6. Jeep on with headlights on the battery reads at 14.25. Also, halogens work fine. Halogens will stay on, LEDs flicker and then shut off

I am no electrical guru...please dummy answers down for me

halogens work fine. Halogens will stay on - So you're saying that if you go back to the OEM headlamps, those headlamps stay on?

If that's the case, then there's nothing wrong with your TIPM and I suspect that the TIPM (via CANBUS) is detecting your LEDs and reacting to it.

This may not be correct, but from what I understand the halogens may *look* like they are running fine because the type of light they are. They don't require the 8v or what not that LEDs do. The halogens will work on 2v, just won't be as bright as they should be.

Even when no lights are plugged in and I'm testing the voltage of the Jeep's H13 harness, I'm only getting 0-2.5v. So it really doesn't matter what lights are attached, I'm not getting the 8v or so that are supposed to be coming out of the harness.

Bottom line, how do I get more than 2v to the original Jeep H13 harness? I assume I need to bypass the PWM which may be faulty

With the key in the OFF position, the headlights get regular 12v dc.
With the ignition ON, they get PWM voltage. It's a 78% duty cycle; 90Hz


The voltage is around 10 or 11 volts, but a meter can't react quickly enough to show the peak voltage. That may be why it appears to have low voltage.

Your relay may not like the PWM voltage. There are ways to make the relay behave. Others who have done this may chime in on the subject.

This is what I was getting at.

I believe you need to use a capacitor (4700uf 35V Electrolityc) between the jeep harness and your relay.

Edit - this is why I hate the CANBUS crap on my JK. All kinds of stuff show low voltage when the engine is running but show a full 12V when key on, engine off.

Actually, LEDs take less voltage to operate than the halogens, so if something were going to work at 2V, it would be the LEDs, not the halogens.

It does matter what lights are attached. If you say that the halogens are working and the LEDs aren't, then it matters and it indicates that the TIPM isn't the culprit and instead it's whatever you're introducing into the system. In this case your LED harness.

So I have the SMS wiring harness that gets powered by the battery. You are saying to take the cable from the SMS wiring harness that is attached to the original Jeep H13 harness and add a capacitor to the wire(s) before the relay box? If so, both the high and low beam wires need a capacitor?

IF I forego the SMS wiring harness and keep my LED lights hooked up with the anti flicker harness/adapter to the Jeep's original H13 harness then I put the capacitor between the anti flicker harness and the Jeep's H13 harness?

Well, that harness looks like it should do what the capacitor does - smooth the CANBUS pulse (•Cleans up pulsed current from CANbus to allow use of relays)... so perhaps your SMS box is bad.

I converted from H13 to H4 and used a combination of relays, diodes, and the capacitor to do mine. I had to use a capacitor on my high beam but not the low beam. Not sure why I didn't have flicker on low, but I don't. The high-beam had terrible flicker.

That SMS box SHOULD be cleaning up that pulse.

Agreed....as well as 4 different sets of anti flicker harnesses I have tried.

Do you know if there is a way I can bypass the PWM by using the parking light wiring? I would assume the PWM is only for headlights, not the parking or even fogs

The fogs are definitely PWM. I don't know about the parking lights.