Aftermarket fogs w/ factory switch?
09-19-2006, 12:11 PM
#1
Senior Member
Thread Starter
Join Date: 07-17-2006
Location: Beyond the Sun....
Posts: 520
Aftermarket fogs w/ factory switch?
Has anyone wired up factory fog light switch to aftermarket lights?
I know that there are 3 wires that plug into the back of the factory switch:
Pin A.....Black/White= Ground
Pin B.....Grey= Instrument Panel Lamps Dimmer Switch Signal
Pin C.....Not Used
Pin D.....Orange = Front Fog Lamp Switch Signal
I know where all the other wiring goes except for the switch. I could only imagine that the Orange wire from the back of the switch has to be wired to back of the relay?
Anyone know for sure?....Thanks
Or if there is a better way?.........Any suggestions appreciated
This is a diagram of what I'm trying to work with minus the indicator light:
I know that there are 3 wires that plug into the back of the factory switch:
Pin A.....Black/White= Ground
Pin B.....Grey= Instrument Panel Lamps Dimmer Switch Signal
Pin C.....Not Used
Pin D.....Orange = Front Fog Lamp Switch Signal
I know where all the other wiring goes except for the switch. I could only imagine that the Orange wire from the back of the switch has to be wired to back of the relay?
Anyone know for sure?....ThanksOr if there is a better way?.........Any suggestions appreciated
This is a diagram of what I'm trying to work with minus the indicator light:
09-19-2006, 12:53 PM
#2
Senior Member
Thread Starter
Join Date: 07-17-2006
Location: Beyond the Sun....
Posts: 520
I think this setup may work better (top picture) and just use the Orange wire off the switch as a "trigger" to the 86 post? Anyone agree or disagree? Sorry about bad pic...........Thanks..
09-19-2006, 02:40 PM
#3
Senior Member
Join Date: 02-01-2006
Location: lockport,ny
Posts: 1,377
The factory fog light setup has the switch going to the BCM (computer) as an input. I don't have the HHR service manual handy right now, so I'll assume that the switch wiring you show is correct.
When you turn on the factory fog lights switch, the signal at the Orange wire (Pin D) will be at GROUND. Notice there is no +12V going to the switch (other than the switch illumination input when the lights are on). To make that work with your relay, hook up terminal 86 on the relay to a +12V source. Then hook up the fog light switch output (Pin D) to terminal 85 on the relay. When the switch is turned on, it will apply ground to the relay and turn it on.
If you are using the factory harness going to the switch, be sure to cut the orange wire and tape it off!! If you don't, then the switch output will still be connected to the computer input. A relay coil can dump thousands of volts into the control circuit when it shuts off (this is how an ignition coil works). The fog lamp switch input at the computer was not designed to handle this voltage and it may damage the computer.
Another option would be to connect the aftermarket lights to the factory system and get a dealer to reprogram the computer to enable the fog lamp system.
Steve
When you turn on the factory fog lights switch, the signal at the Orange wire (Pin D) will be at GROUND. Notice there is no +12V going to the switch (other than the switch illumination input when the lights are on). To make that work with your relay, hook up terminal 86 on the relay to a +12V source. Then hook up the fog light switch output (Pin D) to terminal 85 on the relay. When the switch is turned on, it will apply ground to the relay and turn it on.
If you are using the factory harness going to the switch, be sure to cut the orange wire and tape it off!! If you don't, then the switch output will still be connected to the computer input. A relay coil can dump thousands of volts into the control circuit when it shuts off (this is how an ignition coil works). The fog lamp switch input at the computer was not designed to handle this voltage and it may damage the computer.
Another option would be to connect the aftermarket lights to the factory system and get a dealer to reprogram the computer to enable the fog lamp system.
Steve
09-19-2006, 03:20 PM
#4
Senior Member
Thread Starter
Join Date: 07-17-2006
Location: Beyond the Sun....
Posts: 520
Originally Posted by fastsuv
The factory fog light setup has the switch going to the BCM (computer) as an input. I don't have the HHR service manual handy right now, so I'll assume that the switch wiring you show is correct.
When you turn on the factory fog lights switch, the signal at the Orange wire (Pin D) will be at GROUND. Notice there is no +12V going to the switch (other than the switch illumination input when the lights are on). To make that work with your relay, hook up terminal 86 on the relay to a +12V source. Then hook up the fog light switch output (Pin D) to terminal 85 on the relay. When the switch is turned on, it will apply ground to the relay and turn it on.
If you are using the factory harness going to the switch, be sure to cut the orange wire and tape it off!! If you don't, then the switch output will still be connected to the computer input. A relay coil can dump thousands of volts into the control circuit when it shuts off (this is how an ignition coil works). The fog lamp switch input at the computer was not designed to handle this voltage and it may damage the computer.
Another option would be to connect the aftermarket lights to the factory system and get a dealer to reprogram the computer to enable the fog lamp system.
Steve
When you turn on the factory fog lights switch, the signal at the Orange wire (Pin D) will be at GROUND. Notice there is no +12V going to the switch (other than the switch illumination input when the lights are on). To make that work with your relay, hook up terminal 86 on the relay to a +12V source. Then hook up the fog light switch output (Pin D) to terminal 85 on the relay. When the switch is turned on, it will apply ground to the relay and turn it on.
If you are using the factory harness going to the switch, be sure to cut the orange wire and tape it off!! If you don't, then the switch output will still be connected to the computer input. A relay coil can dump thousands of volts into the control circuit when it shuts off (this is how an ignition coil works). The fog lamp switch input at the computer was not designed to handle this voltage and it may damage the computer.
Another option would be to connect the aftermarket lights to the factory system and get a dealer to reprogram the computer to enable the fog lamp system.
Steve
09-22-2006, 07:51 AM
#5
Senior Member
Join Date: 02-01-2006
Location: lockport,ny
Posts: 1,377
Ok, I've had a chance to look in the service manual to see where everything is.
Unfortunately, the BCM is located in the console, so the orange wire from the switch doesn't go thru the firewall, only down the console to the BCM.
Here's an option:
The relay for the factory fog lamps is in the underhood fuse block. The relay is controlled by the BCM. At BCM connector C1, pin 54 has a yellow wire connected to it. Cut this wire at the BCM. Applying +12 volts to the yellow wire will activate the factory relay and apply power to the factory fog lamp connectors.
Unfortunately, the fog lamp switch has the reverse operation, it applies GROUND when on. This rules out connecting the orange wire from the switch to the yellow wire going to the factory relay. However, you can install your new relay somewhere in the console so that it applies +12 volts (tapped off from somewhere under the dash or console) when you ground the relay control terminal. In other words, relay terminals 86 & 30 to a +12 volt source, terminal 87 to the yellow wire that was removed from the BCM, and terminal 85 to the orange wire from the factory fog lamp switch. Don't forget to cut the orange wire from the BCM as discussed previously.
This option allows you to use the factory relay and lamp wiring under the hood. All your work (additional relay and wiring) happens inside the car in the console. No wires to run thru the firewall. No dealer programming.
The only caveat is that I don't know if they install the fog lamp relay in the underhood fuse block if you don't get the factory fog lamps. Maybe someone else can answer this question or I might go look under my hood to see If I have it (I didn't get the factory fog lamps). Worst case scenario, you have to buy a factory fog lamp relay and plug it into the underhood fuse block.
Good Luck
Steve
Unfortunately, the BCM is located in the console, so the orange wire from the switch doesn't go thru the firewall, only down the console to the BCM.
Here's an option:
The relay for the factory fog lamps is in the underhood fuse block. The relay is controlled by the BCM. At BCM connector C1, pin 54 has a yellow wire connected to it. Cut this wire at the BCM. Applying +12 volts to the yellow wire will activate the factory relay and apply power to the factory fog lamp connectors.
Unfortunately, the fog lamp switch has the reverse operation, it applies GROUND when on. This rules out connecting the orange wire from the switch to the yellow wire going to the factory relay. However, you can install your new relay somewhere in the console so that it applies +12 volts (tapped off from somewhere under the dash or console) when you ground the relay control terminal. In other words, relay terminals 86 & 30 to a +12 volt source, terminal 87 to the yellow wire that was removed from the BCM, and terminal 85 to the orange wire from the factory fog lamp switch. Don't forget to cut the orange wire from the BCM as discussed previously.
This option allows you to use the factory relay and lamp wiring under the hood. All your work (additional relay and wiring) happens inside the car in the console. No wires to run thru the firewall. No dealer programming.
The only caveat is that I don't know if they install the fog lamp relay in the underhood fuse block if you don't get the factory fog lamps. Maybe someone else can answer this question or I might go look under my hood to see If I have it (I didn't get the factory fog lamps). Worst case scenario, you have to buy a factory fog lamp relay and plug it into the underhood fuse block.
Good Luck
Steve
09-22-2006, 08:25 AM
#6
Senior Member
Thread Starter
Join Date: 07-17-2006
Location: Beyond the Sun....
Posts: 520
Originally Posted by fastsuv
Ok, I've had a chance to look in the service manual to see where everything is.
Unfortunately, the BCM is located in the console, so the orange wire from the switch doesn't go thru the firewall, only down the console to the BCM.
Here's an option:
The relay for the factory fog lamps is in the underhood fuse block. The relay is controlled by the BCM. At BCM connector C1, pin 54 has a yellow wire connected to it. Cut this wire at the BCM. Applying +12 volts to the yellow wire will activate the factory relay and apply power to the factory fog lamp connectors.
Unfortunately, the fog lamp switch has the reverse operation, it applies GROUND when on. This rules out connecting the orange wire from the switch to the yellow wire going to the factory relay. However, you can install your new relay somewhere in the console so that it applies +12 volts (tapped off from somewhere under the dash or console) when you ground the relay control terminal. In other words, relay terminals 86 & 30 to a +12 volt source, terminal 87 to the yellow wire that was removed from the BCM, and terminal 85 to the orange wire from the factory fog lamp switch. Don't forget to cut the orange wire from the BCM as discussed previously.
This option allows you to use the factory relay and lamp wiring under the hood. All your work (additional relay and wiring) happens inside the car in the console. No wires to run thru the firewall. No dealer programming.
The only caveat is that I don't know if they install the fog lamp relay in the underhood fuse block if you don't get the factory fog lamps. Maybe someone else can answer this question or I might go look under my hood to see If I have it (I didn't get the factory fog lamps). Worst case scenario, you have to buy a factory fog lamp relay and plug it into the underhood fuse block.
Good Luck
Steve
Unfortunately, the BCM is located in the console, so the orange wire from the switch doesn't go thru the firewall, only down the console to the BCM.
Here's an option:
The relay for the factory fog lamps is in the underhood fuse block. The relay is controlled by the BCM. At BCM connector C1, pin 54 has a yellow wire connected to it. Cut this wire at the BCM. Applying +12 volts to the yellow wire will activate the factory relay and apply power to the factory fog lamp connectors.
Unfortunately, the fog lamp switch has the reverse operation, it applies GROUND when on. This rules out connecting the orange wire from the switch to the yellow wire going to the factory relay. However, you can install your new relay somewhere in the console so that it applies +12 volts (tapped off from somewhere under the dash or console) when you ground the relay control terminal. In other words, relay terminals 86 & 30 to a +12 volt source, terminal 87 to the yellow wire that was removed from the BCM, and terminal 85 to the orange wire from the factory fog lamp switch. Don't forget to cut the orange wire from the BCM as discussed previously.
This option allows you to use the factory relay and lamp wiring under the hood. All your work (additional relay and wiring) happens inside the car in the console. No wires to run thru the firewall. No dealer programming.
The only caveat is that I don't know if they install the fog lamp relay in the underhood fuse block if you don't get the factory fog lamps. Maybe someone else can answer this question or I might go look under my hood to see If I have it (I didn't get the factory fog lamps). Worst case scenario, you have to buy a factory fog lamp relay and plug it into the underhood fuse block.
Good Luck
Steve
Steve, Thanks again for all the info. I'm going to tackle my project this weekend and let you know how things went.
Just as info.... I know that mine doesn't have the relay in the main fuse panel under the hood,(L/S model) or the fog light fuse directly above where the relay is placed. I'm also pretty sure if your vehicle didn't come with fogs, that you need to run a wire from the relay (under the hood) to the lights. I found this thread while doing some homework....Regards
https://www.chevyhhr.net/forums/how-tutorial-library-21/do-yourself-factory-fogs-637/
09-22-2006, 09:55 AM
#7
Member
Join Date: 12-18-2005
Location: Minnesota
Posts: 76
The factory fog switch is a monentary so you would have to hold it all the time you want your fogs on. If you are installing a non factory switch just bypass all the factory wiring and start from scatch.
My .02 wire them up as the factory intendend and have the BCM control them. The factory switch is only back lite it does not indicate on/off of the fogs. The fog indicator is in the dash under the speedo and is controlled by the BCM.
Check out this link. HOW TO INSTALL FACTORY FOG
https://www.chevyhhr.net/forums/showthread.php?t=637
My .02 wire them up as the factory intendend and have the BCM control them. The factory switch is only back lite it does not indicate on/off of the fogs. The fog indicator is in the dash under the speedo and is controlled by the BCM.
Check out this link. HOW TO INSTALL FACTORY FOG
https://www.chevyhhr.net/forums/showthread.php?t=637
09-22-2006, 10:23 AM
#8
Member
Join Date: 12-18-2005
Location: Minnesota
Posts: 76
I should point out all three wires for the switch come from the BCM. The signal wire is only designed to carry enough power to trigger a low level input to the BCM. Hooking even the coil side of a relay will most likely damage the BCM. As FATSUV stated when a coil (even in a small relay) de-energizes it will create a large voltage spike. Not something you want to send to the input side of the BCM. Infact thats why they are sinking inputs (switching neg) they're backwards" for a reason.
My take you proabably spent 17K+ for your car do you realy want to risk blowing out the BCM just to save a few buck by not having to reprogram your BCM. Not sure what they get for the BCM but I'm sure its more than reprogramming.
My take you proabably spent 17K+ for your car do you realy want to risk blowing out the BCM just to save a few buck by not having to reprogram your BCM. Not sure what they get for the BCM but I'm sure its more than reprogramming.
Thread
Thread Starter
Forum
Replies
Last Post