An Alternative method to get the 4/6-hi mod for V8 EXT/XL Owners.

06Envoy

Original poster
Member
Dec 4, 2011
419
This Article describes my modification which is an adaption of the DIODE method to acheive the 4-hi or the 6-hi mod for V8 EXT/XL owners who don't want to remove thier back seat to get to the BCM. This is done by moving the diode installation from the BCM to the underhood fuse box.

* For the I6 EXT/XL owners, do not fret. I have to do my wife's soon. I post up an article for the I6 owners when I get it done.

* I do not claim ownership of this mod. This has been done many many times by many many people across many many types of vehicles. All I've done is adapt it to work for us V8 EXT/XL owners who do not want to mess with thier rear seat.

* This mod should be a prerequisite if installing HID's in your Lows. This mod will eliminate the warm up delay experienced when switching from high's back to lows.

* This mod retains ALL OEM functions. Everything factory still works as intended.

* When installing this mod, Don't be in a hurry! Haste makes Waste! Make sure that you have a lazy afternoon off and have all your items/tools available and verified.


Time to Complete:
1 hour including cleanup

Tools and Items required:
x2 Diodes
x3 Misc lengths of 22AWG wire
x1 Beer
Black Electrical tape
Wire Stripper
Your Soldering Kit


Ready to begin? Here we go!



- I was installing Hid's at the same time so I have all of my items and tools spread out and verified before I begin.
120-albums76-1994.jpg


- Strip both ends of the three peices of wire
- Remove Relay#46. Wrap one end of one peice of wire around pin#5. Reinsert Relay #46. : This is your Low Beam relay.
- Remove Relay#43. Wrap one end of one peice of wire around pin#85. Reinsert Relay #43. : This is your High Beam relay.
- Remove Relay#39. Wrap one end of one peice of wire around pin#85. Reinsert Relay #39. : This is your Fog Light relay.
120-albums76-1996.jpg


- Wrap the end of wire from Relay#39 around the first diode lead that does not have the silver band.
- Wrap the end of wire from Relay#43 around the first diode lead from the last step. It should have the silver band around it.
120-albums76-1995.jpg

- Wrap the end of wire from Relay#46 around the second diode lead that does not have the silver band.
- Wrap the end of the second diode lead that has the silver band around the lead of the first diode lead that also has the silver band around it.
- Stop work. This is where you can go test the system to make sure that all leads are set correctly. Turn your lights on. Check for Lows. Flip the multifunction switch to high beams. Now check for all lights being on. They are? Good, let's keep going!
- Solder all diode lead connections.
- Wrap up the contraption softly with strips of black electrical tape. It should look like this;
120-albums76-1998.jpg


- Replace the underhood fuse block covers.
- Step back with your beer in hand and enjoy your craftsmanship! Job well Done! :hail:
120-albums76-1997.jpg
 

Blckshdw

Moderator
Nov 20, 2011
10,700
Tampa Bay Area, FL
:undecided: Nice to know there's an option where I don't have to try and yank out my back seat by myself. Very nice! :thumbsup:
 

Regulator

Member
Nov 20, 2011
2,496
Blckshdw said:
:undecided: Nice to know there's an option where I don't have to try and yank out my back seat by myself. Very nice! :thumbsup:

There is another method by switching a couple of pins in a wiring harness under the drivers side dash. I have been to busy this week to get to it, but I will get a write up very soon.

OP, nice write up. It looks like this method will save EXT trucks a lot of hassle if they want to do thier lights via the diode method. Nicely done! :thumbsup:
 

Blckshdw

Moderator
Nov 20, 2011
10,700
Tampa Bay Area, FL
Regulator said:
There is another method by switching a couple of pins in a wiring harness under the drivers side dash. I have been to busy this week to get to it, but I will get a write up very soon.

Doesn't that swap the functionality of the flash to pass, and high beams from the multifunction stalk?
 

gmcman

Member
Dec 12, 2011
4,658
Looks cool indeed, but to play the devils card, it's illegal in some states to have more than 4 lit at the same time.
 

06Envoy

Original poster
Member
Dec 4, 2011
419
gmcman said:
Looks cool indeed, but to play the devils card, it's illegal in some states to have more than 4 lit at the same time.

I would imagine that this is true.
So those people may opt for only the 4-hi mod. Or they can live dangerously and go for the 6-hi mod.



Which brings another important safety tip....
Because you are increasing the light output when on high beams, please be considerate of other drivers and turn them off when you see oncomming traffic.
Even if it's far away.
Even if it's on the other side of the divided highway.
Especially if you see red taillights ahead of you....turn off your high beams! :thumbsup:
 

Short Bus

Member
Dec 2, 2011
1,906
Blckshdw said:
Doesn't that swap the functionality of the flash to pass, and high beams from the multifunction stalk?

:yes: That's what the pin swap does :yes:
 

06Envoy

Original poster
Member
Dec 4, 2011
419
Short Bus said:
:yes: That's what the pin swap does :yes:

I saw that mod too...
But in all honesty, I was looking for a mod that didn't take anything away from or do anything wierd to the OEM controls in case my wife took out my truck at night or it got lent out, etc....

I was going for all OEM functions retained.
Flash-to-pass
Perimeter lighting
Auto on-off
Shut-off delay
Fogs on lows still operate by switch
Fogs on led lites up when on (including when on highs)

Again from what I read, and I could be wrong about this, I think the pin swap method messes up the flash-to-pass and the shut-off delay. That wasn't going to be ok for me.

Anyways, both methods have thier merits. It's not about one being better than another.
I just provided an alternative method.
 

Short Bus

Member
Dec 2, 2011
1,906
:goodpost: Well said :thumbsup:

BTW, There's also a way to add fogs by adding a jumper under the dash.
 

Menthol

Member
Dec 8, 2011
177
The list only states 1 beer. I think it's suposed to be 1 for each leg on every relay you have to work on ........... no?:biggrin:
 

06Envoy

Original poster
Member
Dec 4, 2011
419
cody_s said:
Awesome, thanks!

No Problem!


A couple more things to point out.
1) I've asked Roadie to repair the pics in the article. (We can't edit our own posts).
2) Since I've written this article, it applies to every single TrailBlazer or Envoy. I've personally installed this on TBSS, Short wheel base/long wheel base, I64.2l/V8/5.3l/6.0l
. Doesn't matter, if it's a TB or Envoy, then it works. I've had mine in for a year now with no issues. Similar reports from the other guys on the forum that I've installed it on. Again no worries.

This mod has been proven to be safe and reliable and most of all......
It retains completely 100% all OEM lighting functions!
Everything works like it is suposed to with an added benefit of additional lighting when on high beam!
 

07Denali

Member
Feb 28, 2013
71
I'm really interested in doing this mod to the denali. Any chance of some pics? or a better how to? thanks guys
 

Short Bus

Member
Dec 2, 2011
1,906
CdnGMan said:
Ummmm... that's not even close to being the mod that was done to my truck... :no:

But that's not to say that that mod doesn't work... :undecided:

Did Stef do your Quads under the dash?

- - - Updated - - -

CdnGMan said:
Ummmm... that's not even close to being the mod that was done to my truck... :no:

But that's not to say that that mod doesn't work... :undecided:

Did Stef do your Quads under the dash?
 
Dec 13, 2013
1,490
Osceola,Ia
Got a question for you guys that have done this mod. When switching from highs to lows, or using flash to pass, do your fogs go off for a second then come back on?
 

Envoy_04

Member
Jul 1, 2013
749
Midnyteryder02 said:
Got a question for you guys that have done this mod. When switching from highs to lows, or using flash to pass, do your fogs go off for a second then come back on?

When doing the method laid out BY THE OP, it depends on whether you go 4 or 6 hi. With six hi, when changing from hi to lows the fogs will stay on if you have them on via the dash button, but go out otherwise. When using flash to pass, all six will light up, then go off back to whatever you previously had on when you release the stick back forward. 4 hi is the same, just w/o fogs. Hope this helps. :thumbsup:
 
Dec 13, 2013
1,490
Osceola,Ia
Envoy_04 said:
When doing the method laid out BY THE OP, it depends on whether you go 4 or 6 hi. With six hi, when changing from hi to lows the fogs will stay on if you have them on via the dash button, but go out otherwise. When using flash to pass, all six will light up, then go off back to whatever you previously had on when you release the stick back forward. 4 hi is the same, just w/o fogs. Hope this helps. :thumbsup:

Yup everything works just as stated. But when having fogs on with lows, then going to highs they stay on of course, but wen switching back to lows the fogs shut off for a second. You can see the light flicker. I was just wondering if this was normal since I had thought bout putting hids in fogs and thought that it flickering would mess with the hids
 

Envoy_04

Member
Jul 1, 2013
749
Midnyteryder02 said:
Yup everything works just as stated. But when having fogs on with lows, then going to highs they stay on of course, but wen switching back to lows the fogs shut off for a second. You can see the light flicker. I was just wondering if this was normal since I had thought bout putting hids in fogs and thought that it flickering would mess with the hids

It's normal. As you're turning off the highs the power going to the fogs through the jumper you added to the power pin is being cut off. Then the lows come on and at the same time so do your fogs, but now of course the power is coming through the fog relay power pin. The flicker is from the power source switch that occurs.

It doesn't hurt any normal lights, but I'm no HID guy, so I don't know about those.
 

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