Foglights On With High Beams

[r1mechanic]

Hey guys - recently bought a 2016 Sierra Denali and joined the forum. Stumbled upon this thread while clicking around. I always gain so much from these forums, so I thought I'd give back in my first post. Here is a simple solution I made to have the fog lights automatically turn on with the day time running lights - did this with my previous truck as well (2008 Cadillac Escalade). I bought a diode and used some 14 gauge wire I had laying around. I wrapped 14 gauge wire to each end of the diode and sealed it with marine grade shrink wrap (waterproof). I then got into the engine bay fuse box and pulled the fuses for the fog lights (#49) and day time running lights (#28 or #29 - can be either, only need one). When I put the fuses back in I wedged the wire in one of the slots for the fuse connector, one end of the diode/wire goes in the fog light fuse and the other goes in the DRL fuse. Keep in mind the diode is directional (only allows current one way), so if it doesn't work at first just flip the wire around. Now anytime your DRL's are on, the fog lights will automatically come on. No need to push the fog light button. The fog lights also stay on when you turn on your brights. I attached a photo of my set up, it was taken standing over the driver side fender looking at the fuse box. Ask any questions if you got em!

Can you tell me what diode I need? Amazon? I like this in the fuse block idea.


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[midwestdenaliguy]

24 minutes ago, r1mechanic said:

Can you tell me what diode I need? Amazon? I like this in the fuse block idea.


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Here's the exact diode I used, but it looks like it's currently out of stock on Amazon. It doesn't have to be this brand, any 6a 100v diode will work.

 

https://www.amazon.com/ELECTRONICS-NTE5812-STANDARD-DIODE-pieces/dp/B011N9OCV4/ref=sr_1_cc_2?s=aps&ie=UTF8&qid=1533862118&sr=1-2-catcorr&keywords=nte5812

[r1mechanic]

Here's the exact diode I used, but it looks like it's currently out of stock on Amazon. It doesn't have to be this brand, any 6a 100v diode will work.
 
https://www.amazon.com/ELECTRONICS-NTE5812-STANDARD-DIODE-pieces/dp/B011N9OCV4/ref=sr_1_cc_2?s=aps&ie=UTF8&qid=1533862118&sr=1-2-catcorr&keywords=nte5812

Thanks for the idea and help.


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[Racindave]

These are the ones i used. We’ve used them on 4 different trucks with no issues. 

Edited January 3, 2019 by Racindave

[Racindave]

2 hours ago, Racindave said:

 

Edited January 3, 2019 by Racindave
Didn’t read entire post. Bad info.!

[chuckworkb]

i'd like to know how to fix it so, if you select fog lights to be turned on with your low beams, they will come on again after you turn off the truck and then back on again, instead of pressing the button again. 

 

[alkrisma]

me too

[Ballzee]

yeah.. def would also.. i had a few cars in the past where they would stay on thn some don't. its crazy

[bdmd5093]

Just did this fogs on with brights and cargo lamp/bed lights on in reverse mod.   Took about 10 minutes but that was only because I was not sure how far I needed to push the diode leads in so I fiddled around with it for a bit.  Also, I left the connectors plugged in to do it and had no problems.  I may put a piece of electrical tape over the diodes just to keep them from falling out since I ride on a lot of rough roads.  Great, cheap, simple mod and thanks to all for the pointers here and to @pgamboa for the pic on page 46 of this thread.  I can understand why the fogs with brights is not standard (since it may not be legal in some areas), but the cargo lamp/bed lights on with reverse and remote unlock should definitely be standard in my opinion.

[Ravenkeeper]

CA says that you can only have up to four (4) forward facing white lights ON at a time, so some of the '15s and older aren't legal if they do the fogs/highs mod, as some of their lows stay on with their highs.  YES, my '15 was illegal with this mod.

 

 

[Agung Wibowo]

On 7/12/2014 at 9:04 AM, Spurshot said:

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

 

Is it the same BCM Connector color for 2008 GMC Sierra? Because I was looking in another website it should be black color bcm for 2007-2013 sierra.

 

[Spurshot]

I don't have any information on the 08.  

[Szilla]

On 7/12/2014 at 1:04 AM, Spurshot said:

2014 SIERRA SLT FOG LIGHTS WITH HIGH BEAM HEADLIGHTS MODIFICATION

•  

Spurshot, I joined GM-T just to say Thank You for this post.  I did this on my new 2018, and appreciate your time in looking up how to do it!

 

 

[Hillwood]

On 2/10/2019 at 10:06 PM, Ravenkeeper said:

CA says that you can only have up to four (4) forward facing white lights ON at a time, so some of the '15s and older aren't legal if they do the fogs/highs mod, as some of their lows stay on with their highs.  YES, my '15 was illegal with this mod.

 

 

There are a lot of mods that are illegal.. 

Our country and states make laws, with no way to enforce them.. 

Don't let the laws stop you.

[Ravenkeeper]

2 hours ago, Hillwood said:

There are a lot of mods that are illegal.. 

Our country and states make laws, with no way to enforce them.. 

Don't let the laws stop you.

It didn’t stop me, as you could see in the photo. My ‘18 doesn’t violate that law, single hi/low bulbs.