Does anyone know what/where the Daytime Running Light module is triggered by? I'd like to re-wire my fog lights to act as DRL's, but since my '99 was not factory equipped with DRL's or fog lights I'm essentially starting from scratch but I'd like to use any/all OEM wiring that may exist... Thanks for any info!

 

Someone correct me but I thought every car has DRL's. it's on the head light switch. It's in the middle when you pull it out.

 

Nope. Those are parking lights. Daytime running lights are run by a separate module that sits on the passenger side fender. They send juice to the headlights based on input from the Vehicle Speed Sensor (speedo). Standard equipment up here in Canadiana and elsewhere. Not surprising if a WA Jeep has em.

The way the module works is to send low voltage to the lowbeam filament in the headlamps, when the vehicle is in motion, and the high beams are NOT selected. Selecting the high beams will turn em off. The fog relay involvement is that the factory fogs also get killed when high beams are on. I disabled mine when I upgraded my headlight harness as the low voltage was pissing off the Putco relays, but there's no reason you couldn't just use the module to run DRLs with some other light.

 

Wow. Never heard of this one before. Pretty sure my PA XJ doesn't have that!

 

VSS signal... That's what I was after!! Thank you! So now I need to dive in and verify if any of that wiring exists in mine, since it was not factory equipped with DRL's. If I can simply plop in the module and then make my own harness from the module output, I'll be set!!

 

I don't think the harness was on models that were not equipped from the factory. Big reason being that Highbeam Indicator light in the dash. If you unplug the DRL module on mine that little blue light doesn't work anymore, and neither does the fog cut-off. lol

 

Vehicles with DRLs or factory fogs often have an added ground for functionality. I tried to install an upgraded light harness (like Putco) in my Camaro, but it wouldn't work properly because of my factory fogs.
So, I don't know the wiring, but there is probably a ground preventing the DRLs and Highs from being active at the same time.

 

OK so this module/harness... where should it be physically located? I had originally assumed it was just a relay type module that plugged into a slot in the PDC, but after some very brief research is sounds like it may be an actual stand-alone harness and connector somewhere in the engine compartment??

 

Not on our XJs (at least 97+). The DRL module turns off power to the low beams when it senses a request for high beams.

That it is. Like I mentioned it lives on the passenger fender, behind the PDC. I'll snap a pic for ya when I get a chance

 

Good to know. Thanks for the info.

 

When I installed my Putco in the XJ last weekend, I noticed the wonky effects it had with the high beams/low beams due to the conflict with the factory fog setup. On XJ's with factory fogs, there's a 20ga red wire on the driver's side headlight plug, and for it to work as designed from the factory (fogs switch off when high beams are activated), you need to snip that wire and bridge it back to the factory fog relay.

Since I hate the factory fog setup and didn't feel like dealing with that mess, I decided to just pull that fog relay and be done with it. Put my fogs on my car instead--shooting for a light bar w/ dedicated harness/relay in the future for the Jeep.

 

I would greatly appreciate that! I have found a pigtail harness next to the PDC, and it's got a "plug" in it to keep the terminals clean. It's only got 3-wires on it though, but one of them is white/orange, which may be the VSS signal wire according to the diagrame above... Fingers crossed on that, as I can use that to trigger a relay and turn on my fogs

 

Okay so it's sunny AND I remembered. Here ya go, this is right up in the corner above the blower motor. That hard line is for the vaccuum reservoir









The orange caps I should probably replace. They're the various wires I severed trying to turn DRL off.

 

in my opinion you are way over complicating this, heres what i did. i bought an add a fuse and hooked it to a fuse that was only hot with the key on(in the underhood pdc) from there i just wired my fogs as they would have been done normally (these are not factory fogs) so i can control they via a switch or i can just leave them on all the time and they go on and off via the ignition. Heres an add a fuse if you dont know what they are
http://www.parts-express.com/pe/show...pla:sweatdrop:

 

I'd just like to add some info that I found regarding the Putco harness upgrade. I disconnected the DRL module to stop the annoying relay buzz as salad mentions. To get the blue high beam indicator to work again, jump pin 1 and 4 and you'll have your blue high beam indicator working once again.



Props to the fella that runs jeep-xj.info