• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

high beams stuck on after putco / autopal install

kcmudbug

NAXJA Forum User
Location
KC
I ran into some problems after installing the putco headlight harness and autopal housings with stock replacement H4 bulbs. Basically, once the high beams are turned on, they will not turn off unless you turn off the headlights. I also had a phantom high beam indicator...meaning it was very, very dimly lit. I found the answer on CF and thought I would share it here. Apparently this only affects 97 - 01 Cherokees with factory fog lights.

I would encourage you to read the full version below, but here is the Cliffs notes version of the solution: Test to make sure this is the problem by pulling your foglight relay and checking to see if the problem goes away. If it does, the smaller of the two red wires that goes into the stock driver's side headlight plug is a trigger for your fog lights to shut off when your high beams get turned on. It needs to be cut and re-routed to the 87 pin (not 87a!) of your high beam relay to retain factory functionality.

I can't take any credit for it, just happy to find the answer and for it to be so simple. Full version in next post.
 
Last edited:
Anyway, here it is as posted by EZEarl from CF...

If you have stock fog lights on a 97+ and upgrade your harness in a manner that uses the factory wiring to trigger some new relays, your fog lights will have and/or cause issues unless you make some additional modifications to address the problem. It doesn't matter if you use a plug and play harness like the eautoworks or if you split your harness open and completely strip out all the extra factory wiring like I did. The factory fog circuit will cause your new lighting system to not work properly.

If you do nothing, your headlights will work as mentioned above. Low beams will be fine, but after you turn on your high beams, they will not turn off again until you completely turn off your headlights. Big issue here is that when you switch back to low beams, both the high beam and low beam filament will be remain powered causing your bulbs to endure 115W worth of heat output instead of the 55W or 60W that they are designed for. From what I've read this can cause them to overheat and burn out within minutes.

So what is happening? If you look at the driver's side headlight plug (and you have factory fogs) you will notice there are two red wires coming out of one of the terminals. One is a small 18g Red wire which sadly is the stock high beam wire. The other is an even smaller 20g Red wire which ties into Fog Lamp Relay #1 in the PDC. Please keep in mind that Fog Lamp Relay #1 is NOT used to provide battery power to the fog lights the way we commonly use them with aftermarket lighting. It is located before the switch and simply cuts power to the Fog Light Switch unless the Headlight Switch and Beam Selector Switch are in the proper positions. It does this as law dictates that you can't run your high beams and fogs at the same time. Though not a problem here in CA, I've read that states with safety inspection programs will fail your vehicle if the lights don't operate this way.

I dug into the wiring diagrams but had to have kastein help me decipher them because there was something about this circuit that just wasn't making much sense to me. I still don't understand the function of Fog Lamp Relay #1 in its entirety, but we're only concerned with the part that is affected by the headlight harness anyways. Essentially, when your Headlight Switch is off, the relay coil receives no power and therefore won't allow your fog lights to come on. When your Headlight Switch is turned on, one side of the relay's coil receives 12V which causes the relay to activate and send power through to your Fog Light Switch. When you turn your high beams on, 12V is sent out to your headlight socket via the Beam Selector Switch, and then is sent back to the other side of the relay coil via the skinny Red wire on that shared terminal. This brings both sides of the relay coil to 12V, thus causing it to deactivate and turn off the Fog Light Switch. Weird huh? The factory designed it so that the relay is off with both sides at 0V, on with one side at 12V, and then off again with both sides at 12V. While it makes perfect sense now, this is the part that was confusing me.

So what's the problem then? Well, it turns out that even when the high beams are off, there is still approximately 5V on that skinny Red trigger wire for some reason which I still don't understand. While this is obviously not a problem in the factory configuration, it becomes a problem when you are using the high beam wire (which is directly tied into the skinny Red wire) to trigger your aftermarket high beam relay. A typical automotive relay requires approximately 8V to activate and needs to drop to somewhere below 1-5V to deactivate. When you first turn on your lights there is no problem because the phantom 5V is not enough to activate your new high beam relay. When you turn your high beams on, your new relay gets 12V and kicks on. When you go to turn off your high beams, the phantom 5V keeps the new relay from deactivating and voilà, your high beams are stuck on...

So how do we fix this? There are a few common suggestions that are out there that I just wasn't happy with, and a few that sort of work, but not as required by law:
1. Don't use your high beams, new lights are bright enough anyways (OK...)
2. If you have to use your high beams, turn your headlights off briefly to get them turn off (PITA)
3. Pull various fuses (lose your fog lights)
4. Pull the fog lamp relay (again, lose your fog lights)
5. Modify the fog lamp relay (fog lights work, but won't cut out when your high beams are on?)
6. Install a jumper in place of the fog light relay (fog lights work, but switch is always hot?)

One post I saw got it right though. lilredxj99 mentioned it in another thread which I didn't find until after the fact. The details were a little fuzzy and I still thought the issue deserved some further explanation so that's why I just wrote this damn novel...
Oh yeah, so the right way to do it... Cut the 20g Red Fog Lamp Relay #1 ground/trigger wire at the back of the driver's side headlight plug. Extend this wire using your preferred method so that it is long enough to reach your new aftermarket high beam relay. Splice it into the 87 pin (output) of your new high beam relay. If you have two 87's (which is ideal), either one is OK. Do not however use 87a if your relay has it!

Yep, that's it... Your high beams will now turn off when they're supposed to, your fog lights will turn on/off when they're supposed to, and your low beams will continue to work as they're supposed to. Sure you could have skipped all the way down to the bottom and found your answer, but you wanted to know how/why it works, right?
 
Last edited:
The fog light relay coil is using the high beam filament as its path to ground, basically. I installed yet another relay behind the DS headlight to just ground that wire on high beam. That way I'm future proofed for LED headlights or whatever and I can use the opposite terminal on the new relay to control a driving light relay if I want.
 
If you have stock fog lights on a 97+ and upgrade your harness in a manner that uses the factory wiring to trigger some new relays, your fog lights will have and/or cause issues unless you make some additional modifications to address the problem. It doesn't matter if you use a plug and play harness like the eautoworks or if you split your harness open and completely strip out all the extra factory wiring like I did. The factory fog circuit will cause your new lighting system to not work properly.
This isn't going to happen 100% of the time. I have a self built harness on my 2000 and have no problems. I also have factory fogs. I did nothing special to it and the stock wiring is 100% intact. Fog lights still turn on and off normally.

If you look at the driver's side headlight plug (and you have factory fogs) you will notice there are two red wires coming out of one of the terminals.
Maybe that is why I have no issues. I'm triggering the harness relays off the stock passenger side headlight plug.
 
I think it depends on the characteristics of the high beam relay coil on your relay harness and also the fog light relay. The Tyco relays that SM uses actually work fine w/ engine off but extra voltage of engine running makes it act up. To ensure no problems you either need a filament, resistor, something between stock high beam wire and ground or else add a relay as I describe above.
 
The filament in the left side high beam is NOT being used as a ground path. If that was so then my fog lights would not be acting as stock as there is no bulb in that socket.

What is happening is that the no 1 Fog light relay is acting as a disconnect relay. Both relay #1 and #2 are SPDT relays, so they are interchangeable. However, if you look at the PDC layout you see that the output of #1 and #2 relay are on different terminals of the relays. The #1 relay is normally closed at pin 9, which sends power to relay no 2 when the high beams are off, closing the circuit on relay 2 to terminal #12 When the high beams are on the #1 relay closes, disconnecting power to the #2 relay.

Basically when the #1 relay isn't energized it closes the path. When it is energized it interrupts the path, breaking the power to the #2 relay. No grounding through the bulb.

BTW, most of those plug in harnesses do use a low quality relay.
 
Last edited:
Remove fuses 3&4 and see if that helps. Worked for me. My fogs were removed before I bought the Jeep and the relay is still there. That was literally all I did.
 
I used a different harness, it's an ebay one for H4 bulbs, but has seperate groundings for each bulb which is nice. It plugs into the passenger side bulb connection, and I got the stuck hi beams. My fogs already didn't work, so I yanked my fog relay #1. #2 was already missing. Don't really seem to mind, it hasn't effected anything. Using autopal 55/60 bulbs too.
 
Back
Top