You forgot one small detail

Wire in a regular bulb at the main wire from the bcm(brain as you put it) before it branches out to the lights and it would fix the issue with a lot of rewiring

I have been meaning to do it myself just haven't had the time to even mess with it

All that is needed is a small bulb holder(eg 194 peanut bulb) wired in series on the plus or minus side of the main supply feeds(not across or you will drain the battery over time)

FYI keeping the bcm active WILL drain the battery quick I know from experience with my dad's h2 when its cluster went nutty(it would drain the battery in a week)

Shoot me a email and I can show you what I mean

 

You forgot one small detail
Wire in a regular bulb at the main wire from the bcm(brain as you put it) before it branches out to the lights and it would fix the issue with a lot of rewiring I have been meaning to do it myself just haven't had the time to even mess with it. All that is needed is a small bulb holder(eg 194 peanut bulb) wired in series on the plus or minus side of the main supply feeds(not across or you will drain the battery over time)

I thought about this also when we were theorizing with emails. I found two issues with this. I added in a bulb ahead of everything (actually at the point where I have put my tap splice where the add a circuit is). If the bulb is added there for power and then ran to ground, the bulb will always be lit up. It may eventually turn off if the brain goes to sleep (I didn't wait long enough to check) and would then turn back on and power up once the ignition key is cycled by waking up the brain.

The two drawbacks with this are that there will be a light source shining under the dash all the time and even these little 194 bulbs get darn hot if they are incandescent. Secondly, if the brain times out with the key turned off, my cargo lamps in the truck bed will only shine at about ten percent (I have a manual switch by the tailgate) unless I cycle the ignition to reset the brain. My "option A" listed above will essentially do the same thing, just without the added peanut bulb and without the issue of unwanted light or heat.

I may just go that route and then run a dedicated +12 VDC power wire to the truck bed lights.

Edit: I just re read your post and caught wiring the bulb in series instead of parallel. Sorry, I didn't pick that up in the emails earlier either. I think it would need to be on the positive wire ahead of any switches, which is essentially where I have my tap splice inserted. Along the same logic, that is where I tried a load equalizer and also a resistor. Running it parallel kept it live all the time and running it in series on the power wire made it active only when the circuit was closed by turning on one of the light switches. Neither one would wake up the brain though but I have not yet experimented with an incandescent bulb ran in series.

I did find a video on the Yukon forum where a guy just ran a fused always hot +12DVC wire up to the orange input wire in the overhead console, then daisy chained that from the overhead console through the headliner, and into the rear dome light input wire. I know that would also work if I had to run some extra wire. I'm just being stubborn and trying to reverse engineer GM by finding a better way. The easiest way would be to find the main power wires at their source (I think I have one set to the map and visor lamps, a second harness going to the cargo/reading lamps, and a third going back to my cargo lamps) cut those wires and attach them directly to a fused always hot +12VDC circuit. That way they would ALWAYS shine at full power ANY time.

I am pretty sure my reading lamps and cargo lamps are not daisy chained to the map lights. If I disconnect the power wire running up the A pillar I believe my reading lamps and cargo lamps will still function because they have their own harnesses leading back to the brain. That would mean a peanut bulb added for the map lights and one added for the cargo lights.

 

Funny you post this, I made the switch to LED interior lights just 3 days ago. I was curious why my map light was dim, unless I used the dimmer wheel and turned them all on. When a map light is turned on (by the button), and another reading light is turned on (2nd row dome reader), is the map light supposed to turn off as a safety feature or is it related to what is discussed in Retrax's thread? Ill be looking forward to your tutorial, Thank you

 

Funny you post this, I made the switch to LED interior lights just 3 days ago. I was curious why my map light was dim, unless I used the dimmer wheel and turned them all on. When a map light is turned on (by the button), and another reading light is turned on (2nd row dome reader), is the map light supposed to turn off as a safety feature or is it related to what is discussed in Retrax's thread? Ill be looking forward to your tutorial, Thank you

Its a battery saver feature that keeps the lights from draining the battery if you leave a light on
My mom left one of my second row reading lights on one time and I didn't know it till the next day when I came out and unlocked the truck(thankfully it had shut the light off or I would have had a dead battery)

 

IC, well that's good then. Do like how bright the LED's are in comparison. Big improvement.

 

Not sure on the bed light but I can check my
Wiring diagrams to see how its wired up

The rest all go to one main set at the bcm(both hot and ground) adding a regular bulb in series with the circuit(either on hot or ground) should be able to fool the system to think a regular bulb is in all of the map and reading lights

 

Ok, let me know. I am pretty sure my rear dome light is on a separate harness. The wires from the light housing run to the rear window area of the back of the cab.

 

Ok, let me know. I am pretty sure my rear dome light is on a separate harness. The wires from the light housing run to the rear window area of the back of the cab.

Its the same as the others they all use the same power and ground

Which is in this order
Dome orange(hot)
Reading or map light gray/black(hot)
Ground for both circuits (black)

I was thinking that if we were to put a regular small(peanut bulb) in SERIES on the gray/black wire it should trick the bcm into thinking nothing is wrong and everything will work as before we switched to LEDs
FYI use a long life bulb and have the holder in a handy to get to place(eg dash fuse box)!so it can be replaced if it were to ever blow

I am going to have to tackle it soon as I don't want to be working on the truck in the winter(I have a few free days coming up so I may try it if I can get a peanut bulb socket before hand)

 

The wiring is different on my EXT. For the front lighting there are two orange wires one black wire one gray wire with black stripe and a fifth wire (don't remember the color but it only operates the back lighting for the homelink). One orange wire is always hot and a full 12 volts. It is the power wire to the homelink. The gray wire with black stripe is the fade off wire. It pulls a full 12 volts when active and then drops voltage to fade bulbs off. Adding a bulb to that wire will do nothing other than giving you an additional light that will turn on when you,open the door and then fade off with the others.

The black wire is ground for all. The second orange wire on my truck is the power wire that loses voltage when brain is off causing dim led and goes full 12 volts when brain is on giving bright led (see first post). That harness leads back to the brain under the dash. My dome light has a SEPARATE harness which leads from the brain somewhere, to the back of the cab, up the back wall, and forward to my dome light. It has 3 wires. Black for ground, gray with black stripe which ONLY leads to center dome light and fades off, and one orange light which provides the dimming problem to the left and right reading lamps. I do not know at this point where my cargo lamps tie in.

The forward lighting harness appears to be run independent of the dome light harness. If I cut the orange wire for my front console lighting, i am pretty sure my dome and reading lamps will still have power. So...anything done to address the front lamps would not affect the rear lamps unless it was something that constantly kept the brain awake in which case all interior lighting would be provided with full 12 volt power. This is what I tried to explain earlier.

If the small added bulb is wired in series to the front light harness the truck will not see it until another light is turned on within that part of the wiring harness. There would be power ran through the new bulb but it would pull no load until the circuit went to ground, completing the path and switching the led on, also allowing current to flow through the new bulb. Theoretically, the draw would click the brain on and then allow everything to function normally, also allowing the brain to go to sleep when the bulbs were turned off.

The problem lies with the harness running to the dome light and the harness running to the pickup truck bed. Those harnesses are for sure provided power by the brain, but at least in my truck, they do not appear to be daisy chained inline with the front harness. So, if the front harness broke a wire, the dome and cargo lights would still work. I believe all three areas lead to the brain independently. If that is the case, an additional bulb would also have to be wired in ahead of the dome lamp (I should really be referring to this as the reading lamps) area and a third bulb would have to be wired in ahead of the cargo lamps. That way, any one of these three harnesses would signal the brain to turn on when a switch was turned on.

If those stupid Canbus LEDs actually worked, that is exactly how it would fix the issue. I have also seen people wire in a resistor ahead of every bulb power wire (three feeds in my case) which have cured a similar problem just like the Canbus bulbs would but I could not get a resistor to work.

While experimenting with my full time stay awake brain mod, the brain pulled down my battery over three days as I feared it might. I still want to try to figure this out but if all else fails, I know how to fix it once and for all by taking the brain out of the equation. Cut all three wires (front orange feed, dome lamp reading light only feed, and cargo lamp feed). Attach all three wires to one lead running back to my full time add a circuit. That would provide full bright wiring any time I wanted, regardless of if the truck was on or off. The wire would be fused and would only be providing power for my visor, map, reading and cargo bulbs. In the event I accidentally left one of the switches on it would take weeks for one led to kill my battery.

 

I now see my mistake(doh)

Ok the bcm does have three circuits for the interior lights(the others may be data wiring so word of warning be carful around those)

The inadvertent power supply is the orange wire(full 12 volts) for the map and reading lights

The gray is the dome(or door) light power(it does the fade to off)

The other wire going to the home link transmitter is for the dash light(which is a different circuit)that isn't the power wire

I plan on tapping into my map lights soon with a regular bulb and see if it does fool the bcm or not(I am hoping it will work)
If not then we can attack it at the bcm level as all the lights go to the bcm via junction blocks throughout the truck(no matter what body style)

 

Interesting. What I also found on my map light console was one black wire and one yellow wire attached to each bulb. The black wire fed the power and the yellow wire led to ground. I am pretty sure I have fewer interior bulbs than you do with mine being a pickup body. At this point I just really want to have the front visor and map LEDs to work and my cargo LEDs to work. If I can get the reading lamps to work, all the better.

I found a video over on the Yukon forum where the guy basically did what I did. He diode isolated the new wires he ran but did not diode isolate where he tapped into the factory harness. By not adding a diode there, the newly supplied 12 volts will back feed to the brain (is it the BCM?) causing it to always stay on and pull from the main battery, at least that's what it did in mine. The video does show how he daisy chained from the map lights to the reading lights, also adding a diode, only to the reading lamps though. If he had isolated backward from where he tapped in, that might work. It would provide full current forward to the lights but not allow voltage to feed back to the brain. The brain would then no longer be the power source for the lights. Cutting the factory wire at the splice point would do the same thing. I'll look for the video. Found them......See below.......

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This one shows the brain being triggered when he turns on the incandescent on the right and you hear it click on grrrrrrrrrr

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This one explains his wiring fix...

 

Ok, I studied the wiring schematics for my truck. This is what worked for me. Where I had originally tapped into the orange wire, I just ended up cutting it. That isolated the brain from backfeed and gave me a place to splice in the new connection. I taped up the wire which leads down toward the bottom of the dash and back to the brain. I butt spliced the now loose wire which heads up the a pillar and feeds the map lights. I used a butt connector from this wire, to a diode and then to a fused add a circuit which is always hot.

Any time I turn on a switch on this circuit it will get full power regardless if the key is on or not. Everything is working great. This wire is the power wire to my map lights, visor lights, and as an added bonus my rear reading lights are on the same feed. I thought they had a separate harness but they have continuity with my orange wire and work perfectly. All I needed for this was an add a circuit, a diode (not sure that is even needed here) and a 4 inch piece of wire. Less than ten bucks and can be completed in about ten minutes.

If I ever want to revert it back to stock, all I need to do is remove the add a circuit and butt splice the factory orange wire back together. The harness is all wrapped with black electrical tape from the factory. I still need to tackle my cargo bed lamps which are fed from a different wire. The glove box lamp is also on a separate circuit but I don't think I will even mess with that at this point.

 

Wow I see you got around to messing with it before me

If you mind me asking can you email me a pic of what wire is the one?

I will pick up a small peanut bulb socket Monday and see if my bulb trick idea works or not(hopefully it will as I would like a light for the fuse box in the dash)

I have seen the bcm but gaa the wiring is a mess that goes every which way under the dash(I have already been under the dash before but only to add the foot well lights) and swap out my speakers and sub(the sub was a pain but worth the work)

The cargo bed lights are likely on a separate circuit(not shown in my wiring diagram for the interior lights so likely its in a different diagram)
I will check and see what circuit they are on

 

Here is a walk through of what worked with my 2003 EXT. This mod eliminates the possibility of battery drain due to the BCM staying awake by bypassing is all together.


This is what my upper console looks like with the map lights and homelink. Remember to remove the phillips screw at the front of the console closest to the windshield then pull the console down. There are four tension clips that will pull free as you do so.

My truck has a sunroof and onstar. Three wiring harnesses are unplugged to free the console. The larger black plug operates the sunroof, the very small plug goes to the onstar microphone, The remaining white harness is the one we are after. That harness attaches to the homelink and the map lights.

Here we can see the console with the harnesses unplugged. Set the console aside in a safe place.

This is the map light/home link wiring harness which comes out of the roof where you just removed the console.

There are two wires on the top row and three wires on the bottom row. The top wires are for the homelink. You will notice one of these wires is orange. LEAVE THESE WIRES ALONE. The three wires on the bottom row deal with the map lights. The left gray wire with black stripe is the power which fades the lights off when the door is closed. The black wire is ground. The orange wire pointed out here is the wire that leads back to the BCM and causes the dimming problem.

Open the driver's door and remove the side panel for the fuse box. You will see a wiring harness wrapped with black tape and gray foam padding. This is the harness we want. It leads up through the A pillar and to the lights.

Wiggle the gray christmas tree retainer free from the fuse box frame and free up the slack in the wiring harness.

It will pull out from behind the panel and give you extra room to work with.

Peel back the electrical tape and foam padding to expose the individual wires.

Find the PROPER orange wire in the bundle, mine had two of them. Use caution here, you want to make sure you have the right wire! I used a multi meter attached to the orange wire pointed out above in the white harness plug to verify continuity. Cut this wire. Tape up the lower portion of the wire which heads back down under the dash so it can not short out. Strip the upper part of the wire to prepare it for a crimp connector. Just a few more steps. We are almost done!

 

Here is a walk through of what worked with my 2003 EXT. This mod eliminates the possibility of battery drain due to the BCM staying awake by bypassing is all together.


This is what my upper console looks like with the map lights and homelink. Remember to remove the phillips screw at the front of the console closest to the windshield then pull the console down. There are four tension clips that will pull free as you do so.
View attachment 240874



My truck has a sunroof and onstar. Three wiring harnesses are unplugged to free the console. The larger black plug operates the sunroof, the very small plug goes to the onstar microphone, The remaining white harness is the one we are after. That harness attaches to the homelink and the map lights.
View attachment 240882



Here we can see the console with the harnesses unplugged. Set the console aside in a safe place.
View attachment 240890



This is the map light/home link wiring harness which comes out of the roof where you just removed the console.
View attachment 240898



There are two wires on the top row and three wires on the bottom row. The top wires are for the homelink. You will notice one of these wires is orange. LEAVE THESE WIRES ALONE. The three wires on the bottom row deal with the map lights. The left gray wire with black stripe is the power which fades the lights off when the door is closed. The black wire is ground. The orange wire pointed out here is the wire that leads back to the BCM and causes the dimming problem.
View attachment 240906



Open the driver's door and remove the side panel for the fuse box. You will see a wiring harness wrapped with black tape and gray foam padding. This is the harness we want. It leads up through the A pillar and to the lights.
View attachment 240914



Wiggle the gray christmas tree retainer free from the fuse box frame and free up the slack in the wiring harness.
View attachment 240922



It will pull out from behind the panel and give you extra room to work with.
View attachment 240930



Peel back the electrical tape and foam padding to expose the individual wires.
View attachment 240938



Find the PROPER orange wire in the bundle, mine had two of them. Use caution here, you want to make sure you have the right wire! I used a multi meter attached to the orange wire pointed out above in the white harness plug to verify continuity. Cut this wire. Tape up the lower portion of the wire which heads back down under the dash so it can not short out. Strip the upper part of the wire to prepare it for a crimp connector. Just a few more steps. We are almost done!
View attachment 240946

Which diode did u use that pack from radioshack has 4 different diodes

 

Now we get some diodes from Radio Shack, part number 276-1653. These are only a few dollars for a 25 pack.

We take our add a circuit and solder the diode in between it and a wire to run to the butt splice. The diode has only one mark on it. It is a line on one end. You want to make sure you have the line at the end closest to the butt splice quick connect. The diode will only allow current to flow forward so nothing can back feed into your new circuit. If you wire it in backward, your new wiring will not work because the diode will do its' job in preventing the current to flow forward. I like to use the marine style water proof butt splice connectors. They have the added benefit of shrinking when heated with a lighter. A sealant then flows from the middle to further glue together your new butt splice.

 

Tape everything up, snap the wiring harness in, and press your add a circuit in place in the fuse box. Replace the fuse box door and you are done. Enjoy your new LED lights which will not dim. If you piggy back the add a circuit onto a fuse that is only live when your key is on, your lights will only work with the truck running. I used an always hot fuse location. This means if I accidentally leave a switch on, the LED lights will not time out. They will say on but they draw very little current so I am not really worried about my battery running down. This fixed my map lights, reading lights and visor mirror vanity lights. The glove box bulb and truck bed cargo lamps are on a separate circuit and will not be affected with this mod.

 

Awesome work man

I have seen the harness you have in your pics

I will have to dig out my multi meter and probe the harness to see which wire I need to modify