Foglights On With High Beams

CheeseHead...WI · January 21, 2018

What an easy and cheap mod to do...did mine in less than 5min

UnlimitedMatt · March 30, 2018

In case anyone is wondering, the fog light/high beams and cargo light/reverse mods both work on a 2018 1500. I did mine today. The suggestion to cut the tips of the diode was invaluable!

FootballCoach53 · April 2, 2018

I must be an idiot. I still can’t get it right. Lol

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Ravenkeeper · April 3, 2018

23 minutes ago, FootballCoach53 said:

I must be an idiot. I still can’t get it right. Lol

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Post a (closeup) picture of what you have, and some of us will try to get you going in the right direction. May be as simple as tapping into the wrong/adjacent pins.

FootballCoach53 · April 3, 2018

Post a (closeup) picture of what you have, and some of us will try to get you going in the right direction. May be as simple as tapping into the wrong/adjacent pins.

Thanks, man! I’ll have to do that tomorrow!

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DEV1ST8R · April 9, 2018

Fastest, cheapest, most useful mod to date! Works great and only two tries in about 10 minutes. Thanks for the info OP!

Spurshot · April 16, 2018

On ‎4‎/‎9‎/‎2018 at 9:05 AM, DEV1ST8R said:

Fastest, cheapest, most useful mod to date! Works great and only two tries in about 10 minutes. Thanks for the info OP!

It's especially useful if you hook some high power driving lights to the circuit.

14sierra1500 · April 30, 2018

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

OK, well did the modification tonight. Instead of going to the High Beam, I went and ran my Diode into the 22 slot, which is the parking light signal. I tried the lights and everything functioned perfect. Lights on with Low Beams, High Beams, and when switched to parking lights they stayed on as well. All I can say is best 0.50 cent mod ever!!!!

Which color plug is the 22 pin on. I know the fog relay is on the brown just want to make sure I put the diode in the right plug.

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Ravenkeeper · May 1, 2018

Hi (18), Lo (22), & Fog (10) are all on the brown plug.

deputy · June 12, 2018

Try this website, it has a lot of good stuff.

http://www.gen5diy.com/GMC/Sierra/

2018deepocean · June 17, 2018

So looking at my harness pin 10 is solid brown I have a 2018 LTZ use this one ? Anyone have a schematic or know if anything changed on the 2018's? Anyone with a 2018 LTZ accomplished this successfully?

TX LIMO · June 17, 2018

So looking at my harness pin 10 is solid brown I have a 2018 LTZ use this one ? Anyone have a schematic or know if anything changed on the 2018's? Anyone with a 2018 LTZ accomplished this successfully?

According to UnlimitedMatt on post #647 it worked for him and his 2018. May want to message him to see if anything different.

Delivered via my cellular device using a mobile chat forum thingy.

Racindave · June 17, 2018

27 minutes ago, 2018deepocean said:

So looking at my harness pin 10 is solid brown I have a 2018 LTZ use this one ? Anyone have a schematic or know if anything changed on the 2018's? Anyone with a 2018 LTZ accomplished this successfully?

Worked on my 2018 ltz. I didn’t pay any attention to wire color just the pin location.

Edited June 17, 2018 by Racindave