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2002 Full Time DRLs - Instructions for UnderHood Mod

I have done this mod and have had it running for a couple weeks.. Since doing this mod I have occasionally had both turn signals come on when using the left turn signal only. Not sure how the parking lights got involved since I have no connections to the parking lights...

I won't duplicate this on the other threads about the different years but It is a bad idea to do this in this manner. The positive lead is common and the BCM pulls down the relay's negative side of the coil. The BCM outputs have a limit on the current they can handle and I suspect GM never intended to have more than relay controlled in this manner. I do not know what the current limitations are for the BCM and I am sure GM over engineered them if we have 4 EXTRA relays running off one output but I am rethinking how this should be done.

If you do this mod and your truck starts acting weird or you Blow your BCM you have been warned...

To PROPERLY do this mod insuring no BCM damage I believe requires some wiring beneath the fuse panel and requires the addition of a new relay wired in parallel to the current one for each light you want to have on. (Low beam, DRL, Fog)

Use the posting I had earlier about the pin usage of the relays and identify what each pin does.

I should look up the wiring on each of the relays and offer the proper wiring but I won't do that until I do this myself.

Basically you need to wire the new relay so the switched contacts 30/87/87a are wired to the same wires as the same pins on the factory relays. You need one relay for each light you want to turn on, for all of the lights to be controlled you need 3 relays.  (High beam is a "trigger" so it doesn't need a relay)

Chose either pin 85 or 86 to be the ground and the other to be the +12. Should not matter which is which.

Ground your ground pin on all of your added relays to the body. (Use a star washer between the body and your connection. A soldered or crimped connector is the best connection to the ground wires is best option here. Very little power goes through this wire so you don't need a big one.)  (up to 3).

For the positive lead you need to pull this from the switched side of the relay you want to feed from. (Ex. The High beam light... Use the lead from the 30/87/87a pins that is positive ONLY when the lights are on.)  If you are going to do more than one "trigger" you need to isolate them with Diodes with the line on the diode pointed in the direction of the relay you are switching.

So assuming you want to do the all on high mode you will run a lead from the high beam switched to all of the relays without need of a diode.
If you want to run the full time DRL along with all on high you will need to also run the DRL from the low beam but you will need diodes on the leads from the high beams and the low beam to the DRL relay so that when the low beam only is on it doesn't back feed to the high beams and light them up. Not to mention will likely blow a fuse since the low beam circuit is not large enough to run both low and high beams.

This works because now you are running the lights off the powered relays and NOT the BCM. This thus protects the BCM from potential damage and all of your lighting should work without issue. I have some small DEI security relays that I will use for this. No need to use the large 30/40 amp relays. The MOST you are going to pull, assuming 65 watt bulbs can be figured easily.  65x2 (for 2 65 watt brights) = 130 and 130 / 12 = 10.8      (For figuring amperage draw the formula is  Watts / Volts = Amperage so in this case it ends up being 10.8 amps at 12 volts)  So a small 20 amp relay such as those from DEI will work just fine. You can also look at the relays in the circuit and see they are small as well. The DEI ones are real nice because they are compact and already prewired.

I should also note that by wiring the relays in parallel with the original factory ones you are preserving the original factory operation and just adding to it. When the add on relay is on it will not affect the factory relay in any way and vise versa. However someone might get confused if they pull the factory relay and the lights still light up... ;)

At some point this summer I will do this mod myself and document with wire colors and pictures.
 
Lots of info here.  Thanks for taking the time to put this together.

I did this mod a few years back (on my 04 Z71) using the original configuration by Vertabatt of diodes plus added Sylvania Silver Star Ultras high and low bulbs.  It has worked flawlessly ever since.

Retired old guy.
 
Just be careful.. The BCM was never intended to run this many relays... Mine is acting weird since I did this mod and I will be redoing mine with 3 relays and I will document what I do and upload pictures here when I am done. It will be a little more work but is assured to not mess up the BCM in any way which is possible with this mod as written. (My left blinker is acting weird since I did this mod. Both blinkers come on some times instead of just the left so it looks like a hazard light instead of a turn signal.)
 
redheadedrod said:
Just be careful.. The BCM was never intended to run this many relays... Mine is acting weird since I did this mod and I will be redoing mine with 3 relays and I will document what I do and upload pictures here when I am done. It will be a little more work but is assured to not mess up the BCM in any way which is possible with this mod as written. (My left blinker is acting weird since I did this mod. Both blinkers come on some times instead of just the left so it looks like a hazard light instead of a turn signal.)

I had some odd things like that happen to my 02 a few years ago (both turn signals with one, left turn when the brake was pressed, right signal solid when on).. Turns out, it wasn't the BCM. The trailer plug adapter was corroded and causing a backfed into the system. $9 for a new one, and never had the issue again.
 
Thanks for the input.. Thing is it doesn't happen all the time and when it does happen I can turn on the right signal and then the left signal starts working right again. This started happening after I did this mod. As I said, i will be redoing this with relays in parallel and will document it with pictures and share...

I have since done the 4 light brake/turn signal lighting on my truck and installed LED tail lights with the required load resistor for the turn signals and passenger side brake light (for cruise control)and nothing has changed with the intermittent left "hazard" turn signal... 

I won't reiterate my previous concerns about just putting diodes on the relays but I will say this mod is really bright... My HID fogs with the low beams and the extra bright high beams really lights up the roads...
 
I second the trailer plug.  The only thing I used this mod was the low beam on with the high beams, and fogs on with high beams.  Its working flawlessly, but using the diodes, the wires are so small you would have minimal stretching on the relay socket.  But the mod is at your own risk.  I am glad Rod has posted.  He has outlined the dangers of doing this mod, SO heed his warning and make a better informed decision about this.  (I had no idea, but now I know, I'm going to stick with it.)  With my experience, haven't had any issues, But I haven't did the whole mod.  I am only using 2 diodes.

Will
 
i think if this mod caused other electrical issues more ppl would have posted them
this thread was posted back in 2006, thats 9 years ago, a long time for problems to occur
if the mod is done correctly, there should be no issues IMO
i did this a few years back and experienced no issues so far but like will i only did hi-beams and fogs but i also also wired the fogs through a switch so i can turn the mod on and off as i dont use my fogs very much
since doing the mod ive also installed HIDs in lows highs and fogs

i also had a 96 gm pick up and did a similar mod on the highs and had no issue on that truck either
 
I just got done researching the under hood fuse center and it is not as obvious as I had hoped.

It "Appears" that everything is done internally in the fuse center and my desire to parallel install relays won't be as simple.

Will require 4 relays, 4 fuses and a power source to power all of the light sources.

I didn't realize each headlight has a 10A fuse for it. And separate feeds from the fuse center.

I found the voltage supply for Fog lights, low beams (r & l), High beams (l & r) and DRLS.

The fuses go on the supply voltage for each relay on the powered (non coil side). 1 relay for DRL's, 1 for Fogs, and 1 each for each low beam. I would use the same size fuses as already in the fuse box. (10a for the headlights etc.)

We use 2 diodes to pull from the supplied voltage on each of the high beams. This then goes to the positive side of the coil on the relays for lowbeams and fogs. We could just pull from one headlight and forgo the diode but this will trigger the relays no matter which headlight is on if one blows its fuse.

To grab the low beams we would pull off the switched power lead of our new relays and use 2 diodes like we did with the high beams and use that to power the positive side of the coil for the relay driving our DRLs. 

The ground side of our relay coils can be combined and go to any ground location. (bolt that attaches to the body is good enough)

We can grab our power to supply the switches side of the coil from the main power lead into the fuse box. When you pull the secondary cover you can see the access to the main supply to the fuse box. There is a place for a fuse for "customer applications" at this location too or you can just pull power from the main supply.

So we have both sides of our coils attached (ground to a common ground, the low beams and fogs pull the positive side from the hi beam feeds from the fuse box, the drl pulls from our new relays suppied voltage leads.)
The "common" pin of the relays switched power goes to our new fused ower sources...
The "switched" pin of our relays goes to the Supply voltage of the associated relay (DRL, Low Beams L&R and Fogs)

To tie into the supply voltage lines I have always cut the insulation and moved it back to access the wire, solder my new wire to it then wrap this new connection with Scotch 33+ electrical tape.  We will only be taping into the existing lines not cutting the wires.

But...
(next message)
 
Having said all that...

Since I haven't heard of any issues as of this point with the BCM this modification might be more trouble than it is worth.

I still strongly suggest using very small diodes and soldering them to the relays instead of putting them in the sockets as this is how I did mine. I will try to take a couple pictures of mine and attach them to this message as they are.

If I DO decide to go ahead with the above mentioned modification I will document it with pictures.

Rodney
 
Ok I am in the process of doing this modification with BCM safe installation...

Finding out some interesting information... am taking pictures while doing this.. Not a bad project...

I have a bunch of very small diodes I bought a while ago.. I am thinking about setting some up for use in the trucks... Will use clear heat shrink tubing and likely use some very small wire with them...  Not sure yet.  Might solder up like 20 of them so they are available if anyone wants to do them. I still strongly suggest soldering to the relays themselves (And will show a picture of mine that I did this way..) Soldering to the relay makes it harder to swap out if the relay goes bad but doesn't damage the socket in any way...

Rodney
 
I had posted this in another thread so I guess I should post it in the right area also. Enjoy.

You can find as a Fleece all on light module or a fleece FPE-GM-ALO-0307 module


MS03 2500 said:
Well I was perusing the diesel forums over the weekend and I ran across this It's a Fleece Performance all on high Board that you put under the relays to do the all on high mod. I really did not want to put in the diodes in so for 20 bucks plus shipping I did this. It came with a spade terminal adapter in case you want to add some other lights.



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Sorry it's a bad pic,but it's just a normal 03-06 fuse box
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Hey everyone - I'm a new member but wanted to post on how easy this mod was to complete using the detailed instructions provided. I used amber led 3157s and they turned out great....Thanks again!
 
I bought the Fleece PCB for the fusebox & got it installed this weekend. I soldered the spade connector on it in hopes that I could use it to run the 24" LED light bar on the front bumper. The documentation says:

Add the supplied spade terminal to provide a signal ground when the high-beams are turned on. This will allow you to control an accessory relay with the high-beam switch.

WARNING: The spade terminal signal ground is NOT intended to provide a high amperage ground. It is only rated for a signal ground that will control a relay.


Upon installing the PCB, I found the spade terminal has +12 volts on it. Supposedly it's supposed to be a ground switch. But it has + 12 volts only when the low beams are on. If I turn the high beams on, + 12 volts at the spade terminal goes off.

Not sure how I'm supposed to use this.
 
The 12 volts is coming from the low beams. Use the wire from terminal 85 from the LED relay to attach to the spade terminal. If I remember right you had a LED light on the switch for your additional light bar so you may have 2 wires on terminal 85 (one for the led and one for the ground for the switch) figure out which one for the led and disconnect it and cap it off so it does not ground out.
 
I had a chance to look at the truck again this afternoon. There is +12 volts at the spade at all times, ignition on or off, headlights on or off. The only exception to that is when I turn on the high beams.

The wiring harness that came with the LED lightbar has a single plug that goes to all 4 of the relay connections. I think I understand what your saying, but it won't be so easy as just removing one spade connector & moving it.

off-road-atv-jeep-led-light-bar-wiring-harness-40-amp-relay-on-off-switch-11.jpg
 
So I did this mod many, many years ago. Decided to go Amber LEDs. After inserting the 2nd, nothing worked. Found a loose wire from wig wag mod and just removed that mod. Sockets are back to factory, but no power to sockets while running. Took the fuse box apart and did a continuity  test from DRL socket royal blue to the double one you move in the mod, all good. Test the ground in the socket, also good. Checked all 4 pins for the DRL relay socket, 14 volts only on pin 30 (upper right side of relay socket). DRL 10A fuse  is also good. Another thing is suddenly my AC clutch won't engage either and there seems to be no voltage on that line. Could be related. 

Where does the DRL voltage originate from?
 
They both seem to be on the ign e fuse
 

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You are so right sir. Before you made the post (which I thank you very much) I gave up and concentrated on the AC. Found a diagram Shape Shifter posted which showed the ING-E fuse. I then tested the DRL and saw it had power too.

Thanks again for posting!   :cheers:
 
So I had another problem that may have been related. The daylight sensor was working almost backwards. In the morning when it was overcast and dim, the headlights were off. That afternoon when it was bright and sunny, they were on. Now that the I look at the first diagram it makes sense that there was power missing from the circuit. What is strange is that would work at all. That part I don't understand.
 
On the 02s the ign E circuit does not power the BCM so the light sensor would have been working. The BCM uses it to ground the circuit. My manual is off line right now, but I suspect it may have been in a default mode to make sure some type of front light was on.

Back in the 02 - 03 years DRLs were mandatory one of the reasons why we can't turn them off.
 
I found this mod about 2 weeks ago, but I finally did it tonight. At first, I did not think I had enough electrical knowledge to complete it, but after seeing this mod over and over again in the message boards, I gained enough confidence to try. It turns out it is simple. This mod took me less than 10 minutes (I only did FTDRL's).

Let me know what you think!
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Don't worry, the perimeter lighting still works with this mod
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Different lighting
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Michael
 
Good for you.  Many people are scared of electrical mods but they aren't that hard to do with good instructions.

(Easy for me to say, I'm an Electrical Engineer!  >:D)
 
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