Diode Conversion for All Lights On High Beams


  1. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I've only seen write-ups for 07 and older vehicles. I don't know NNBS trucks, at all, but supposing NNBS still have an under-hood fuse box and also supposing NNBS still use the same relays (in a relatively close cluster like they are in 99-06's) for high/low/fog lights, then extrapolation of these instructions should let you get the job done. (Note that the instructions didn't tell me how to have fogs come on with low beams, but it was intuitive enough when I saw what was being done and how.)

    If you're willing to take a shot ... knowing that you're in uncharted waters and knowing you accept the risk for any/all things you do, then read onward...

    Read the linked instructions (http://www.chevyavalanchefanclub.com/coppermine/albums/userpics/25638/ftdrlnstall.pdf) thoroughly so that you are familiar with the relays, their holes, the location of the holes, etc. Once done, locate the under-hood fuse box of your NNBS truck (presumably it still has one!) and check the diagram on the underside of the lid to see if you can find relays for HDLP-HI, HDLP-LOW, and FOG LP. (Important: find the relays, not the fuses. Hopefully their denotation hasn't changed ... or if it has, it's intuitive.)

    If all three relays are within a few inches of one another then you have a good sign. Your next step should be to see if the HDLP-HI and HDLP-LOW relays are the same (look at the numbers on the relays) ... while the FOG LP relay has a different number. If so, then we're on the right track and have a good bit of parity with the 99-06 relay setup. You last step before determining it's worth trying should be to remove one of the relays and check the underside of it to make sure the pin holes are marked and that they match the same pin hole notation as the 99-06 relays. (I wouldn't expect a visual shape/size match to be enough, as I've seen relays shaped differently that had the exact same pin notation and did the same thing. So check the pin notation.)

    If everything, so far, is a match then you're likely good to connect the heat-shrink wrapped N194 diodes as follows:
    * From hole of HDLP-HI to FOG LP
    * From HDLP-LOW to FOG LP
    * From HDLP-HI to HDLP-LOW (Only if you want low beams AND fogs on with high beams; skip this diode if you don't want that.)

    Understand that a diode is simply a semi-conducting device that allows current to flow in only one direction, thus the black stripe of the diodes should be on the FROM side of the connections you're making. Also, you'd only use ONLY the 85 hole of the any/all of the relays you work with, for this.

    Last edited: Nov 9, 2011
  2. aloxdaddy99

    aloxdaddy99 Rockstar 4 Years 1000 Posts

    Surreal thanks for the help. Me and electricity don't get along to well. I had a 440v cord arc in while I was plugging in a line a few years ago so I am a little gun shy when it comes to electrical work.
  3. CowsPatoot

    CowsPatoot Member

    I jumped on here to ask about this exact mod, and I am glad I did some searching before posting. But...it has raised a question. In pic 10 of the PDF (the one that shows all 5 diodes), wouldn't diodes 1 and 3 be redundant? If Diode 1 were removed, the fog lights would still come on with the high beams because it would get the signal through diodes 2 and 5. If Diode 3 were removed, it you would still have FTDRL through diodes 2 and 4.

    I know, I know...I tend to over-analyze these kinds of things. But I won't put my truck at risk by blindly following instructions that I don't fully understand...and just because you find it on the internet doesn't mean it is accurate.
  4. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I'm still running the mod and it's been fine for weeks. (As always, though, modify at your own risk.) I'd suggest putting the diodes in and testing them one at a time (as I did). You can do them in any order you like...
    Last edited: Dec 1, 2011
  5. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    I think you are right. I think the picture is more descriptive of adding diode 5 for fogs with lows. right above it says to do it in the combinations based on what you want. but yes I think if you just wired like the pic those would be redundant. I think it more showed all the combinations on one pic moreso that do all 5 like that. Not sure if it would hurt but its meant for combos. as stated before in the thread, on mine I have diodes 1,2 and 5 but probably could do with out 1, looking at it more closely, since I have fogs with lows and highs and lows with highs.
  6. 5Cent

    5Cent New Member

    Ran this mod on my 01 Duramax for 3years....loved it!

    Now I wish I could figure out a way to have the fogs on automatic and all lights on in the new 2011.
  7. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    If the 2011 uses relays for each then the same concept should apply. If not, educate me -- what's it use?!
  8. aloxdaddy99

    aloxdaddy99 Rockstar 4 Years 1000 Posts

    I just went to do this last night. When I pulled the cover off of the fuse panel I noticed that it has HDLP RT and HDLP LT. So I tried to install the diodes to one side hoping or better yet praying that it would make at least one side work like I want (fogs on Low). No dice. I didn't want to mess anything up so I pulled the one diode out that I had installed. This was after I had to solder on a llittle piece of wire (20 gauge) to get the diode to reach to the fog light relay. Any ideas?
  9. 97killverado

    97killverado New Member

    I have a 1997 Chevy 1500 with out fogs but i am planning on installing hids, will this mod work on HIDs if not can someone guide me in the direction i need for my style truck with HID i just want highs and lows on.
  10. PantheraUncia

    PantheraUncia Rockstar 3 Years 1000 Posts

    This is pretty cool, but I do have question, I thought it was not "street legal" at least in NC to have additional driving lights on when the high beams were on? some how I remember people being pulled for that? but you can have as many as you want on when using low beams? Might be wrong. kinda like using HID's without the proper projector casings..... you will blind people.

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