Foglights On With High Beams

[Spurshot]

This was on the Duramax forum. I believe it is for a GMT 900. But the principles are likely applicable to a K2. Use this information cautiously.
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"This is a write-up for how to make your low beams and/or fog lights stay on when you switch to high beams...This mod costs all of about $1 and should take no more then 15 minutes..its very very easy and use's the trucks own built in fuses and relays. Credit for this goes to Will from duramax diesels...i just made some additions and modifications..

All you need is a set of diodes that you can get from your local Radio Shack. The part number that I used was 1N4004. I have read that 4001,4002,4003 and 4004 will all work. These diodes come in a 2 pack and cost $.97.

You will do this mod under the hood at the fuse block on the drivers side of the truck. Make sure that the truck is off before reaching in there. You shouldn't need to unhook the batteries or anything like that.

On the bottom of the relays is the numbers for the different pins. You will be using the 85 pin for these mods. Also, on the bottom of the lid of the fuse block is a diagram showing the numbers of the pins along with which relay goes where. The 3 relays that are used are in the lower left hand corner of the fuse block

Hi-lows on at the same time.
You will need to connect the 85 pin of the low beams relay to the 85 pin on the hi beams relay. Make sure that the "bottle cap (or end with the stripe)" is going towards the hi beam relay. You can either wrap the wire around the metal pin or slide it into the hole that the pin goes into. Either will work.

Hi-fog on at the same time.
For some reason GM decided that when your high beams are on, your fog lights don't need to be(actually i believe this is a law) . Well I like my fog lights on adding more light. With the hi beams on adding a lot of light, then the fog lights on adding more light can't be a bad thing right?

To do this you will need to connect the 85 pin of the fog lights to the 85 pin of the hi beams. Make sure that the "bottle cap (or striped end)" is going towards the hi beam relay. Again you can either wrap the wire around the pin or push it into the hole that the pin goes into. If you are doing the lows plus the fogs it can be a little tight on the 85 pin of the hi beam pin. For this I wrapped one diode around the pin and the other got pushed into the hole with the pin(i pushed both into the slot...they fit you just need to push down hard on the relay) . You will still have control of your fog lights on low by switch but by doing this the fog lights will always be on with hi beams.

This Mod works perfectly with HID's as well as regular bulbs.

The pic shows how I have it wired. Sorry for the poor picture but hopefully the labels will help better explain things. the second pic is what the diode pack looks like from radioshack..its on the left

Edited July 12, 2014 by spurshot

[fondupot]

Pics are loading for me at work since I'm guessing you used imgur? Either way, give it a try and see if it works. But I was under the impression the new trucks have the lights fed through eh BCM and "tricking" them with the diodes wont work like on previous model trucks.

[Full Lock]

I only see words... I like pictures damn it

 

Nice write up though thanks

[Spurshot]

double post

Edited July 12, 2014 by spurshot

[Spurshot]

My take on this mod is that it jumps the relays, which are most likely downstream from the BCM, and no matter what the BCM is doing the power is switched to the fogs. I dont think the BCM is between the main fuse panel and the lights.

 

I downloaded the wiring diagrams from GMupfitter.com so I'll check it out.

 

 

http://www.gmupfitter.com/

[fondupot]

Let us know if it works out. If it was as easy as jumping the relays like the older trucks. I would do it.

[Spurshot]

Here's the circuit. BCM is between the dash switch and the fuse/main buss as I suspected.

 

[Spurshot]

OK, After struggling thru the schematics and online mods of past models all evening, I figured it out. This is for a Sierra and should be the same for the Silverado.

It involves pushing one Diode into the backside of a connector on the BCM, jumping between two wires. That's it! Piece of cake.

• 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.

It works great. More later. I took pics and have the connector pin schematic .

Edited July 12, 2014 by spurshot

[Spurshot]

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

Edited September 29, 2017 by spurshot

[Sabla]

This was on the Duramax forum. I believe it is for a GMT 900. But the principles are likely applicable to a K2. Use this information cautiously.

------------------------------------------------------------------------------------------------------------------------------------

"This is a write-up for how to make your low beams and/or fog lights stay on when you switch to high beams...This mod costs all of about $1 and should take no more then 15 minutes..its very very easy and use's the trucks own built in fusses and relays. Credit for this goes to Will from duramax diesels...i just made some additions and modifications..

 

All you need is a set of diodes that you can get from your local Radio Shack. The part number that I used was 1N4004. I have read that 4001,4002,4003 and 4004 will all work. These diodes come in a 2 pack and cost $.97.

 

You will do this mod under the hood at the fuse block on the drivers side of the truck. Make sure that the truck is off before reaching in there. You shouldn't need to unhook the batteries or anything like that.

 

On the bottom of the relays is the numbers for the different pins. You will be using the 85 pin for these mods. Also, on the bottom of the lid of the fuse block is a diagram showing the numbers of the pins along with which relay goes where. The 3 relays that are used are in the lower left hand corner of the fuse block

 

Hi-lows on at the same time.

You will need to connect the 85 pin of the low beams relay to the 85 pin on the hi beams relay. Make sure that the "bottle cap (or end with the stripe)" is going towards the hi beam relay. You can either wrap the wire around the metal pin or slide it into the hole that the pin goes into. Either will work.

 

Hi-fog on at the same time.

For some reason GM decided that when your high beams are on, your fog lights don't need to be(actually i believe this is a law) . Well I like my fog lights on adding more light. With the hi beams on adding a lot of light, then the fog lights on adding more light can't be a bad thing right?

 

To do this you will need to connect the 85 pin of the fog lights to the 85 pin of the hi beams. Make sure that the "bottle cap (or striped end)" is going towards the hi beam relay. Again you can either wrap the wire around the pin or push it into the hole that the pin goes into. If you are doing the lows plus the fogs it can be a little tight on the 85 pin of the hi beam pin. For this I wrapped one diode around the pin and the other got pushed into the hole with the pin(i pushed both into the slot...they fit you just need to push down hard on the relay) . You will still have control of your fog lights on low by switch but by doing this the fog lights will always be on with hi beams.

 

This Mod works perfectly with HID's as well as regular bulbs.

 

The pic shows how I have it wired. Sorry for the poor picture but hopefully the labels will help better explain things. the second pic is what the diode pack looks like from radioshack..its on the left

Thanks for info

[Spurshot]

Let us know if it works out. If it was as easy as jumping the relays like the older trucks. I would do it.

 

Are you done yet? ......How about now?

[CoasterCOG]

I just ordered a pack of 100 diodes off Amazon for less than it would of cost me to drive to Radio Shack and buy one. Once I get them in I'll give this a shot.

[Spurshot]

There's a Radio Shack on the west side of 23 by Walmart if you don't want to wait.

[CoasterCOG]

Yeah but Radio Shack is $1.50 for one. I got 100 for $4 something. I'm planning to pass the extras around. ;)

[Spurshot]

Yeah but Radio Shack is $1.50 for one. I got 100 for $4 something. I'm planning to pass the extras around. ;)

 

You're gonna spend $45 in postage sending them around being a nice guy .