Modifing fog light relay
11-13-2013, 07:09 PM
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I'm standing here about to put the putco harness in my 2000 jeep cherokee WITH FACTORY FOG LIGHTS. I know I will run into some kind if issue with this and understand I need to either extend some 20 guage wire for high beams to shut off fogs to the 87 relay pin or alter the fog light relay. My question is either
1) how to alter the relay to make the fogs come on whenever I want and basically fix the fog light with putco harness combo
2) figure out which pin is number 87 on these unlabeled relays
1) how to alter the relay to make the fogs come on whenever I want and basically fix the fog light with putco harness combo
2) figure out which pin is number 87 on these unlabeled relays
11-13-2013, 09:40 PM
#4
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Suppose to be the fix:
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?
Suppose to be the fix:
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?
11-13-2013, 11:57 PM
#5
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Join Date: Sep 2013
Location: LI, NY
Posts: 362
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Year: 2000
Model: Cherokee
Engine: 4.0
Courtesy of EZEARL
Suppose to be the fix:
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?
Suppose to be the fix:
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?
11-14-2013, 05:58 AM
#6
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11-14-2013, 12:28 PM
#8
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Yes and no,your fogs will turn on but when you flash the hi-beams they won't turn off.If you want them to work as factory,you have to connect the red trigger wire to the positive for the highs on the new harness.The reason been is that the relay is grounded thought the bulb filament and when you flash the lights you are applying a voltage to that wire and the fog light relay opens.
11-14-2013, 01:18 PM
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Yes and no,your fogs will turn on but when you flash the hi-beams they won't turn off.If you want them to work as factory,you have to connect the red trigger wire to the positive for the highs on the new harness.The reason been is that the relay is grounded thought the bulb filament and when you flash the lights you are applying a voltage to that wire and the fog light relay opens.
11-14-2013, 01:26 PM
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Which relay did you do this to? One of the new ones with the harness or the foglight relay in the power center? And when you say bend the pin, do you mean bend it totally sideways out of the way so it no longer plugs into the socket? And have you done the harness install already and have no weird issues with the headlights staying on even after you shut them off, unless you flick the highbeams? That is my issue.
11-14-2013, 01:31 PM
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Cool. I had seen something on the net where the guy just jumped the highbeam terminal to the ground terminal on the unused drivers side h4 socket to solve the problem. But I couldnt understand how that would work unless you clipped the highbeam power wire off of it first. It seemed to me that it would be fine until you hit the highbeams, then something would pop.
11-14-2013, 04:37 PM
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Which relay did you do this to? One of the new ones with the harness or the foglight relay in the power center? And when you say bend the pin, do you mean bend it totally sideways out of the way so it no longer plugs into the socket? And have you done the harness install already and have no weird issues with the headlights staying on even after you shut them off, unless you flick the highbeams? That is my issue.
Last edited by 2000chersport; 11-14-2013 at 04:43 PM.