How To: 99-02 Hi 6 with Diagram

chef choy said:

tried to do this a while back. Shouved the wire in there, and had a hell of a time getting the relay in there as well. Thought I had it and half way home my lights (headlights) started to flicker on and off. I took the wire out thinking it was causing my relay to not seat well enough. Few days later I tried it again and really made sure everything was connected well and same thing....bout halfway home the flicker. I pulled over and it was still flickering when the car was not moving and making a noise from the fuse box. I put the wire in the upper left prong in the grey relay, and the upper right prong on the black relay like what is circled here in red......

Anybody with input?

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chef choy said:

I soldered the wire to the ends of the diode because the diode itself was not long enough like the guy in the op described. It looked exactly like the way this guy had his.

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**Oops just noticed I put the Relay back in upside down, but it doesn't matter it's still plug 86 that you need to wire into.

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Red Rocket said:

Another member asked for a picture of mine so here are some. I soldered the diode to the wires and used heatshrink but left the area of the diode with the band uncovered so I was sure to install it in the right direction. The physical layout is just as described by the OP, just the number on the headlight relay terminal is 85 not 86.

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l2yan said:

This is for Hi 6 and Auto Fog lights (with Headlamps) -

First off new to the forums, love all the info I've found here and wanted to share something that took me probably 5+ hours to finally figure out via Searching the internet as well as trial and error. Finally finished all this at about 3am working in cold weather but wanted to get it done!! **Note this will also prevent the .5 sec lag your fog lights will get when switching from High Beams Back to Low Beams. This was key in what I was trying to do so that my HID Fogs would last a little longer by not resparking when I wanted to flash brights =). With this set up you cannot turn your Fog Lights off while your headlamps are on. I'm sure there is a way to do it but I'm happy with finally getting this project over with ....... for now.

What you need:

-15-20 Mins of your time
-(1) Diode - 1amp or 3amp with 50+ volts
-About 1ft of 14-18gauge wire
-Solder
-Heat Shrink or Electrical Tape

To Start off this is assuming you know how to do the easy and basically free way of the Hi 4 for the 99-02 models. In a nutshell tap the yellow wires from the headlights and ground them using a scotchlok or any other form of quick splicing. You can do this from under the Fuse Box or right at the headlight assembly.

Here is a nice write up by Yuke2k:
http://www.tahoeyukonforum.com/forum/showthread.php?t=8742

Now to convert the rest:

- You will need a 1amp or 3amp - 50v+ Diode. You can purchase a 2 pack at radio shack for like $1.50.

-Take 2 small (14-16 Gauge) wires and connect them to both ends of the diode so you end up with an extension since the diode itself is not long enough to reach the necessary relay. You can strip the ends of the wires and solder them to the diode or any other ways that you prefer to do so.

-As you already know from your searches 99-02 models have only ONE relay for headlamps instead of separate hi/lo relays, so many of the how to's do not apply to us =( I did this on a 2001 Yukon Denali XL.

-First find the Headlamp relay on the left hand side of the Fuse Box. Remove it and insert the end WITHOUT the grey band into the top left plug (86).

-Second find the Fog light relay toward the bottom right as shown in the pic below. You will be connecting the end of the Diode with the Grey band into the top right slot (87).

-You can now replace the replace the relays into their original spots making sure that the ends of your wires are securely touching both the fuse male ends as well as the inner metal of the sockets. You can then route the wire however best suits you.


That's pretty much all she wrote: This is maybe a 15min job if you know how to do it correctly. Don't ask me why they go into the particular plugs. I tried every possible way until this one finally worked after countless hours of fruitless googling.

Picture below of my fuse box. The big grey square fuse is the Headlamp Relay and the Rectangle Black Relay is the Fog lights. **Oops just noticed I put the Relay back in upside down, but it doesn't matter it's still plug 86 that you need to wire into.

This is with Headlamps and Auto Fog Lights

This is the end result of the Hi 6. Don't make fun of my color matching I'm not done yet =)

**Sorry pictures had to be angles down cuz my crap camera couldn't handle the glare Q(^.^Q)

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Red Rocket said:

If you want to do it your way without a diode, I guess that's your risk. Why bother asking if it's OK if you're going to do it anyway? There's nothing in the instructions about pin 30 so don't worry if the relay has one or not. Sometimes relays have extra pins that aren't used in some applications. If you look at my pictures a few posts back, you can physically see (with my relays removed) which locations to hook the wire to. If you hook it between these 2 places and you blow a fuse, guess what? You need a diode. Here's the instructions from the OP:

-First find the Headlamp relay on the left hand side of the Fuse Box. Remove it and insert the end WITHOUT the grey band into the top left plug (86).

-Second find the Fog light relay toward the bottom right as shown in the pic below. You will be connecting the end of the Diode with the Grey band into the top right slot (87).

So if you see in my picture, it's the TOP LEFT of the headlamp relay and the TOP RIGHT of the fog light relay.

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