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New relay box/ Headlight harness problem with high beams

K

kboyts

NAXJA Forum User
Location
NE ohio
I made a combination fitch relay box/Headlight upgrade harness. Heres my problem-

If I have the switch in low beam position and turn the lights on all is good. Then switch to high beams, still all good. But when I turn it back to low beam, the lows come on but the highs dont switch off and both burn at once. Then the only way to get the high beams to turn off is to turn the lights off completely then back on.
 
a wiring diagram or pictures would be helpful
 
We theres obviously a short somewhere... Since the box is your own creation id pull it apart and try to find where your short is coming from.

For us to even do anything, as tomcat said, we'd need pictures and a schematic of your setup.
 
Now Im wondering if I grabbed a odd type of relay when I built the box. I found this on another site-

The SPDT is commonly used as a door lock relay and is easily identifiable by the terminal markings on the the bottom, the output terminals are marked as 87 and 87a. The SPST relay is commonly used as a fog light relay and is identified by haveing the two output terminals marked 87.

I just grabbed a handfull out of a car at the junk yard. Have to look at my spare one and see in the morning.

I dont really have a schematic. Male H4 plug plugs into passenger headlight to get high/low signal to power relays(pin 85). Power goes into relays on pin 87, then out to lights on Pin 30, pin 86 to ground.
 
outlander said:
do you have factory fog lights?
Click to expand...

well they are there but both have been busted since I got the Jeep. I have aftermarket fogs to replace them but havent installed them yet

Someone on JF just answered my prob. Its the factory wiring for the fogs, long story short it runs thru the headlights to turn them off with the highs blah blah blah. But if I pull the factory fog fuse (which I dont need anyways) it will solve the issue.

Now to dig up a diagram of the factory fuse box to find the fog fuse.
 
Last edited:
I think you problem is transient voltage being present. I have a similar problem with my setup. my guess is that you have voltage on the relay from the headlight switch at all times...but not the 12 volt required to energize the relay, but about 6 volts(I have measured this voltage with a multimeter). while that 6 volts is not enough to energize the relay, it seems to be enough to keep the relay energized even when you switch the hi beams off. when you turn the hi beams on and then try to turn them off, they stay on?? if so, turn the lights off, then back on, are the high beams still on, if not, I think you have the problem I described.
 
I answered on JF but will answer here too. This is an issue with any 97+ XJ that has factory foglights and only uses 1 of the headlight plugs to provide a signal to the relays that power the new wiring harness. It has something to do with the grounding of the foglights and it keeps the highbeams after they are initially turned on. The easy way to solve this issue is to remove the foglight fuse in the kick panel. I also belive that if you use both headlights to provide the power signal to the relay that this is not an issue.
 
the_weirdo said:
I answered on JF but will answer here too. This is an issue with any 97+ XJ that has factory foglights and only uses 1 of the headlight plugs to provide a signal to the relays that power the new wiring harness. It has something to do with the grounding of the foglights and it keeps the highbeams after they are initially turned on. The easy way to solve this issue is to remove the foglight fuse in the kick panel. I also belive that if you use both headlights to provide the power signal to the relay that this is not an issue.
Click to expand...
this is what I love about this place...somebody always has the answer. I'm gonna try it when I get home...thanks alot!!!
 
kboyts said:
well they are there but both have been busted since I got the Jeep. I have aftermarket fogs to replace them but havent installed them yet

Someone on JF just answered my prob. Its the factory wiring for the fogs, long story short it runs thru the headlights to turn them off with the highs blah blah blah. But if I pull the factory fog fuse (which I dont need anyways) it will solve the issue.

Now to dig up a diagram of the factory fuse box to find the fog fuse.
Click to expand...


Thats what I was getting at.....
 
from fitches how-to for the harness

I hesitated so long to publish this writeup because there is a small flaw in the configuration of the wiring if you have factory fog lights. With the harness installed and the fog lights turned on, if you turn your lights on with the low beams active, then go to hi beams and back to low, all of the lighting elements in the bulbs will stay illuminated. Essentially giving you the light output of 4 headlights. While this is good for your visibility, it will cause your lights to burn out in short order.

If you take a look at your stock driver’s side H4 headlight plug, you’ll see not 1 but 2 wires connected to the hi beam terminal.

This wire is used to tell the XJ that the hi beams are on/off and allows the fog lights to operate accordingly. The law states that fog lights can only operate when the low beams are on. This connection sends a current through the system that makes its way back into the new harness and keeps the hi beam relay connected when it shouldn’t. If you cut the lights off and back on again, everything operates normally.

I searched around for a simple fix to this but I never found one that I was comfortable with. My fix was to pull the fog light relay from the PDC under the hood. This will keep the feedback from happening but it also takes away your fog lights. This hasn’t been an issue though because I have plenty of light output from the brighter light. :)
Click to expand...
 
I have a 98 with factory fog lights. I need to do the harness upgrade. Will I run into the same problems ? The foglights don't work, and I wanted to run the stock switch to a relay which controlled the aftermarket lights once I get a good bumper and some good lights.
 
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