Foglights On With High Beams

Justin Ross · February 20, 2017

Have you seen this harness from Gen5DIY?

http://www.gen5diy.com/GMC/Sierra/P-P-Harnesses7/Foglamp-Harness8/Sierra-Foglamp-Harness/

Justin Ross · February 20, 2017

I have not, thanks for sharing. However I would still like to have on/off functionality of my light bar with the high beams on. It seemed practical to utilize the fog light button since it is more or less unused when the high beams are on.

Shredzy · February 21, 2017

I have not, thanks for sharing. However I would still like to have on/off functionality of my light bar with the high beams on. It seemed practical to utilize the fog light button since it is more or less unused when the high beams are on.

Could contact Gen5diy and see if they could help you out?

They may be able to customize the harness for your needs?

No Tyme · February 21, 2017

For a few buck extra I had Gen 5 add and extra power wire on my harness for the light bar in my future. It will be controlled by the high beam switch.

Justin Ross · February 21, 2017

Could contact Gen5diy and see if they could help you out?

They may be able to customize the harness for your needs?

I will look into this, thanks.

Spurshot · February 22, 2017

I will look into this, thanks.

A work around would be to do the 10-18 mod, then put a switch between the fog harness and the relay for the light bar. This would allow disabling the light bar when the high beams are used.

bgweed · February 23, 2017

Ok, so I spent the last hour reading through this thread and this specific question wasn't asked. So the BCM handles the task of turning the fogs off with the brights and there hasn't been anyone who has successfully attempted to bypass this either...but with that said, is it possible, with the combination of jumpers, switches or relays to use the unresponsive fog light switch to toggle on/off a light bar? it would seem that You would need to intercept the fog light switch before the BCM and have that go to a relay that goes to another relay that is tapped into the high beams signal. This would allow power to the relay controlled by the fog light switch only if the highs at on. Or would I be able to tie into the high beams power source going to the fog light controlled relay allowing the use of only one relay rather than two. Any ideas?

A work around would be to do the 10-18 mod, then put a switch between the fog harness and the relay for the light bar. This would allow disabling the light bar when the high beams are used.

High Beams Off: Fog switch functions normally

High Beams On: Fog lights always on, Fog switch operates light bar

If that's the functionality you want, then you could do the following. I'm assuming the fog switch is actually a pulse (active low or active high).

- Use Gen5DIY harness to keep fogs on with High Beams, with the add-on high-beam trigger option (or some other way to get the status of the high beams, like directly off the stalk?)

- Tap into the fog switch output upstream of the BCM.

- Make a circuit with a D-type flip flop using the high beam trigger as the Enable input and the fog switch signal as the Data input.

It would be cheap to do (other than the Gen5DIY harness) but it would be pretty tedious.

Edited February 23, 2017 by bgweed

Ravenkeeper · March 2, 2017

2014 SIERRA SLT FOG LIGHTS WITH HIGH BEAM HEADLIGHTS MODIFICATION

This mod will let you use the fog lights on low beam same as factory. On and off with the fog light button.

When the fog lights are turned on while on low beam, then the high beams are either flashed or turned on and then off, the fog lights remain on when going back to low beam.

When the high beams headlights are switched on, the fog lights come on also. You cannot shut the fog lights off with the high beams on. When going back to low beam, the fog lights go off if they were off prior to switching high beams on.

Find the BCM under the dash, just to the left side of the steering column, right behind and above the OBD2 connector. It's a black box about 7" square and an inch thick. It will have 7 connectors in the lower edge of various colors.

Pull the BROWN connector loose. There is a little tab you need to squeeze inward to release it.

Look at it closely, there are tiny numbers at the corners to give you pin location reference. Use my attached connector photo and the numbers on the connector, along with the colors of the wires to locate the proper wires.

Locate pin #10 with the Brown and White striped wire. This is the Fog light signal wire for the relay.

Locate pin #18 with the Brown and Violet striped wire. This is the High Beam signal wire for its relay.

Take a 1N4004 diode and push the wire lead of the diode in along side the wires with a pair of needle nose pliers. You need to push hard to get it to slide in about 1/4" so it will stay snug. Make sure the marked end of the diode (stripe) is toward the High Beam.

You can put a piece of electrical tape over the bare diode leads or you can slip a piece of heat shrink over the diode before you install it and shrink it after pushing it in. But there's really no need as these are switched Ground leads, not power.

Put the BROWN connector back in the BCM.

YOU'RE DONE. THAT'S IT.

The BCM is behind this area

This is the BCM.

In this picture, my arrows point to the rows to intersect the proper wires.

The diagram below shows the connector oriented as you see it in the photo above so you can locate the correct pins.

Rectifier Diodes are available at any electronics store or Radio Shack.

http://www.radioshack.com/product/index.jsp?productId=2036270&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032230

When this thread first started, it started out as Fog Lights on with High Beams.

Pins #10 & #18

Then it was determined that #10 & #22 was better as the fog lights would be on with low beam AND stay on with High Beam.

So then everyone moved to 10 & 22

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Set up my lights out in the SUN (62F, feeling like 85). Fogs on with HI's, and cargo on with reverse. Thanks for the photos Spurshot & PGamboa (respectively). Took me about 30 minutes on the headlights/fogs, ended up having to remove the brown plug, disconnecting my remote start connections, and my second diode. And about 10 minutes and two attempts/operational checks to get my reverse/cargo lights connected, with the first headlight diode (was salvageable).

LO's before mod

HI's before mod

ALL FWD WHITES w/ HI's ON, after mod

REVERSE/Cargo mod

linkz1 · March 3, 2017

I have my light bar on a switch with relay, how Can I hook it to switch off high beams when the switch is on but not when the light bar switch is off. I know where the pin on the brown plug is, but isn't it the ground side of the circuit?

Trippstarr · March 4, 2017

If someone in San Antonio can do this little mod for my fatass I'd appreciate and buy you a 6 pack of your choice lol

pgamboa · March 4, 2017

I have my light bar on a switch with relay, how Can I hook it to switch off high beams when the switch is on but not when the light bar switch is off. I know where the pin on the brown plug is, but isn't it the ground side of the circuit?

I can't answer your question but can tell you that this diode mod does use the ground side of the circuit.

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If someone in San Antonio can do this little mod for my fatass I'd appreciate and buy you a 6 pack of your choice lol

LOL. I'd fix ya up but I'm in Dallas.

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bgweed · March 4, 2017

I have my light bar on a switch with relay, how Can I hook it to switch off high beams when the switch is on but not when the light bar switch is off. I know where the pin on the brown plug is, but isn't it the ground side of the circuit?

If I understand you correctly, you want the light bar to come on with the high beams, but only when you also have the light bar switch on at the same time. I think your best bet may be the 5thGenDIY harness with the high-beam trigger. You can route the trigger (which is active-high, as in "on" is 12V) through any on-off switch, then to the relay. That way your switch interrupts or allows the high-beam trigger to determine whether it turns on your light bar. You are correct in that the BCM pins operate by grounding (called active-low) to turn something on.

If someone in San Antonio can do this little mod for my fatass I'd appreciate and buy you a 6 pack of your choice lol

If you find yourself in Houston, I have a diode with your name on it.

Ffkomo · March 4, 2017

Anyone know if there is a way to have the fogs come on automatically with the DRLs? Maybe a jumper from fogs to pin 7-right front DRL? Or pin 1/2 supply voltage? Any ideas?

arcasey · March 6, 2017

Anyone know if there is a way to have the fogs come on automatically with the DRLs? Maybe a jumper from fogs to pin 7-right front DRL? Or pin 1/2 supply voltage? Any ideas?

What make and model truck do you have?