Fog lights on without headlights...
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Joined: Apr 2011
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The fog light circuit is overly complicated in the Gs. It has been that way since the beginning. The major issue is that the fog light switch is not a typical switch, but instead it is part of a multiplexed input system connected to the BCM (it is muliplexed with the left turn signal, one position on the head light switch, and one other input that I don't remember what it is). From the BCM it doesn't get any easier - there is logic in the BCM that determines if the headlights are on AND the fog light switch is on and if both are on it sends a signal over the CAN bus to the IDPM under the hood. The fog light relay is integrated in to the IPDM making it virtually impossible to connect to the coil of the relay. Out of the IPDM the fog lights are powered by two separate, but common, wires.
If you only want the lights to come on with the parking lights you can install a relay under the hood, power the contacts from the battery and feed both fog light wires AFTER you disconnect them from the IPDM (if you don't it will backfeed power in to the IPDM and do weird things like keep your ignition powered after you take the key off if the parking lights are still on). I would NOT recommend driving the fog lights directly off the parking light signal without a relay - the parking light circuit was never designed to drive two fog lights in addition to the parking lights.
Another thing you can is install a switch in the cabin and use it to drive the coil of a relay instead of the parking lights.
uzbeckuz did you get your module working? If the fogs turn on with both the turn signal and the fog light switch they connected one of the inputs incorrectly. Instead of the module looking at both sides of the multiplexed circuit the module is looking at one leg and most likely constant power on the other. Hooking it up like that will make the fog lights turn on with each different multiplexed input.
The KPtech module is not a very easy module to install. Most installers will not have the tool required to verify the multiplexed BCM wiring (an oscilloscope is needed). Since you are connected to data lines it can be difficult to verify and troubleshoot. The best thing to do is to have the BCM pinout for your exact year and model and make sure you connect to the correct pin numbers.
If you only want the lights to come on with the parking lights you can install a relay under the hood, power the contacts from the battery and feed both fog light wires AFTER you disconnect them from the IPDM (if you don't it will backfeed power in to the IPDM and do weird things like keep your ignition powered after you take the key off if the parking lights are still on). I would NOT recommend driving the fog lights directly off the parking light signal without a relay - the parking light circuit was never designed to drive two fog lights in addition to the parking lights.
Another thing you can is install a switch in the cabin and use it to drive the coil of a relay instead of the parking lights.
uzbeckuz did you get your module working? If the fogs turn on with both the turn signal and the fog light switch they connected one of the inputs incorrectly. Instead of the module looking at both sides of the multiplexed circuit the module is looking at one leg and most likely constant power on the other. Hooking it up like that will make the fog lights turn on with each different multiplexed input.
The KPtech module is not a very easy module to install. Most installers will not have the tool required to verify the multiplexed BCM wiring (an oscilloscope is needed). Since you are connected to data lines it can be difficult to verify and troubleshoot. The best thing to do is to have the BCM pinout for your exact year and model and make sure you connect to the correct pin numbers.
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Joined: Apr 2003
Posts: 318
Likes: 174
From: SoCal
uzbeckuz did you get your module working? If the fogs turn on with both the turn signal and the fog light switch they connected one of the inputs incorrectly. Instead of the module looking at both sides of the multiplexed circuit the module is looking at one leg and most likely constant power on the other. Hooking it up like that will make the fog lights turn on with each different multiplexed input.
The KPtech module is not a very easy module to install. Most installers will not have the tool required to verify the multiplexed BCM wiring (an oscilloscope is needed). Since you are connected to data lines it can be difficult to verify and troubleshoot. The best thing to do is to have the BCM pinout for your exact year and model and make sure you connect to the correct pin numbers.
yea mine does the same thing... but i left the fogs on all the time
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Joined: Jan 2014
Posts: 116
Likes: 17
From: Ontario, Canada
The fog light circuit is overly complicated in the Gs. It has been that way since the beginning. The major issue is that the fog light switch is not a typical switch, but instead it is part of a multiplexed input system connected to the BCM (it is muliplexed with the left turn signal, one position on the head light switch, and one other input that I don't remember what it is). From the BCM it doesn't get any easier - there is logic in the BCM that determines if the headlights are on AND the fog light switch is on and if both are on it sends a signal over the CAN bus to the IDPM under the hood. The fog light relay is integrated in to the IPDM making it virtually impossible to connect to the coil of the relay. Out of the IPDM the fog lights are powered by two separate, but common, wires.
If you only want the lights to come on with the parking lights you can install a relay under the hood, power the contacts from the battery and feed both fog light wires AFTER you disconnect them from the IPDM (if you don't it will backfeed power in to the IPDM and do weird things like keep your ignition powered after you take the key off if the parking lights are still on). I would NOT recommend driving the fog lights directly off the parking light signal without a relay - the parking light circuit was never designed to drive two fog lights in addition to the parking lights.
Another thing you can is install a switch in the cabin and use it to drive the coil of a relay instead of the parking lights.
uzbeckuz did you get your module working? If the fogs turn on with both the turn signal and the fog light switch they connected one of the inputs incorrectly. Instead of the module looking at both sides of the multiplexed circuit the module is looking at one leg and most likely constant power on the other. Hooking it up like that will make the fog lights turn on with each different multiplexed input.
The KPtech module is not a very easy module to install. Most installers will not have the tool required to verify the multiplexed BCM wiring (an oscilloscope is needed). Since you are connected to data lines it can be difficult to verify and troubleshoot. The best thing to do is to have the BCM pinout for your exact year and model and make sure you connect to the correct pin numbers.
If you only want the lights to come on with the parking lights you can install a relay under the hood, power the contacts from the battery and feed both fog light wires AFTER you disconnect them from the IPDM (if you don't it will backfeed power in to the IPDM and do weird things like keep your ignition powered after you take the key off if the parking lights are still on). I would NOT recommend driving the fog lights directly off the parking light signal without a relay - the parking light circuit was never designed to drive two fog lights in addition to the parking lights.
Another thing you can is install a switch in the cabin and use it to drive the coil of a relay instead of the parking lights.
uzbeckuz did you get your module working? If the fogs turn on with both the turn signal and the fog light switch they connected one of the inputs incorrectly. Instead of the module looking at both sides of the multiplexed circuit the module is looking at one leg and most likely constant power on the other. Hooking it up like that will make the fog lights turn on with each different multiplexed input.
The KPtech module is not a very easy module to install. Most installers will not have the tool required to verify the multiplexed BCM wiring (an oscilloscope is needed). Since you are connected to data lines it can be difficult to verify and troubleshoot. The best thing to do is to have the BCM pinout for your exact year and model and make sure you connect to the correct pin numbers.
I've got a Canadian G with the DRL, The DRL is run to my low beams. I've tried taking the DTRL fuse out and the low beams are still on. Is it programmed into the BCM? Or can I somehow tap into that current?
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Joined: May 2014
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Joined: Apr 2015
Posts: 186
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From: Greater Atlanta, GA
Did you read through the thread? You can hook them up to parking lights instead of low-beams to have them run that way. Or you can check out a site that does after market fogs (like Diode Dynamics, not a plug per se, but I know they have instructions) or the DIY subforum section here and you can hook up fog lights to their own circuit. Typically it is done for people who want to run fogs as a show-light system so that they can have crazy colors and what not when sitting parked but not need the head/parking lights on.
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Joined: Nov 2014
Posts: 33
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Thanks for the info! I read through the thread and most people suggest the KP technologies module, but I read their installation instructions and it looks a little too complex for me (need to solder and an oscilloscope).
