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Discussion Starter #1
I did the following mod in 15 minutes. Man is it BRIGHT in front of my truck now.

Pooohwee to the 135 dollar wiring harness mod. Who needs it? My mod is Bright as the sun and NO problems.

Heres the mod I followed. Thanks to whoever posted it and made it up.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Keep in mind this is on a 2003 GMC - other years may be different, even 2003 chevrolet may be differant although I would think it would be the same. For all lights on with high beams:

The bcm is under the steering column, I had to remove the dash panel to get to it. There are 3 larger 24 or so pin connectors on it. The one I am referring to is the 24 pin on the left side.

This connector has 2 rows of 12 pins, one above the other. There are pin numbers associated with them but they were hard to read so I'll explain it like this:

Top row: 1 2 3 4 5 6 7 8 9 10 11 12 -we'll call T

Bottom row: 1 2 3 4 5 6 7 8 9 10 11 12 -we'll call B

T1 is black-white and is High beam control- tap into this and run to a spst (2 terminal) switch, if you are going to use a switch to disable this mod. On the other side of the switch solder 3 diodes with the band ends towards the switch. I used 1n4005 diodes. Now for each of the other ends of the diodes you will solder a short length of wire on and tap into these leads as follows:

T4- is green black and is DRL control

B4- is pink and is low beam control

B5- green white and is fog lamp control

When you're done make sure to insulate each of these ends of the diodes and wires from each other and everything else. Start the truck,turn the headlights on if it's not dark, and with you're new switch off everything should work as before, or as normal. Turn the switch on and with you're high low beam lever in the low position you're low beams and fog lamps should work as normal. Flip to high beam and everything should come on. All we're really doing here is operating the relays under the hood that turn these lamps on normally. There should be no problem with power as they are still getting power the factory way. My only concern is the grounds on the headlamps, I'm hoping they don't run too warm running both lamps at once, and I don't know if both lamps are grounded together or if they have individual grounds. I may have to upgrade the grounds if they give trouble. Hope this is somewhat understandable!Click on image to open in new window

Further note- if you are testing with the ignition switch off the DRLs will not come on at all, that's why I said start you're truck in the testing. If you don't want to install a switch to bypass this mod just connect the band ends of the diodes directly to the T1 black white wire.
 

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That sounds like fun and all but not to rain on your parade, there is an easier way, you can buy this neat little connector with the diode plugs already done for like 12 bucks, then all you have to do is cross the headlight wires over with the connector and run the wire to the lower driving lights and they will all be on when the high beams are on.


12 bucks, 5 mins tops... Just FYI


Oh have no idea where to get the connector, the guy that tinted my windows did it for me. I will ask him. I have a 2004, so it was easy.
 

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Discussion Starter #3
I went 1 step more. I took the bulbs out of the fog lights and replaced them with 9005 bright lights (high beams) bulbs. When I flip the high beams on its like a 747 landing lights came on in front of my truck.

Yeeee Hawwww............

BRIGHT
 

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problemchild said:
I went 1 step more. I took the bulbs out of the fog lights and replaced them with 9005 bright lights (high beams) bulbs. When I flip the high beams on its like a 747 landing lights came on in front of my truck.

Yeeee Hawwww............

BRIGHT







Better watch for meltdown of the foglight housings......
 

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FYI, each bank of headlights share a unique ground... Right low/high beam on one, and left low/high beam on the other. Here is the schematic.


 

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Thanks to Army for the initial posting on this all lights mod. All credit to him for trying this out first & this great posting!!
 

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Discussion Starter #7
Bubz

Is there a way to just ground each light to the frame?
Is the power going through the relays or does it have something to do with the power/ground?

Why on earth did the stupid engineers make this so difficult? Stupid dumbass engineers.......
 

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Sure, ground the wires to the frame and they'll be on all the time! Battery won't last too long though. May have to leave your truck running 24/7/365 though.



The power is going through the headlamp relays and it does have to do with the ground. A switch in the BCM closes to ground it's circuit which energizes a coil in the headlamp relay and pulls in the contacts to complete the circuit through the headlamp.


It's not that difficult. Stupid dumbass biz owners.........






regards,


a stupid dumbass Engineer
 

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Discussion Starter #9
Minn-Kota

I was talking about GMC engineers.
The design is piss poor dont you admit?
Why make lights turn off when you need to see better?
Cars for decades had all the lights come on with high beams.
And lastly, I dont read schematics that well. Its not my expertise. But if you understand programming a SQL server I will hire you at 300.00 dollars per hour. Not everyone understands everything. I am better then average with computer networks and software. How well do you do that?

a not so stupid not so dumbass biz owner
 

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I'm not sure, but I think the point bubz was making was not to the relay control grounds but rather to both lamps on each side share a common ground. Therefore if the ground is designed to carry the current of one lamp at a time, when you add the other lamp and run both at the same time, you may be overloading the common ground. One would need to know the wattage or current draw of each lamp and the current carrying capability of the common ground to determine for sure.


BTW, the $135 harnesses eliminate this problem by supplying separate grounds for each lamp.Edited by: CntrlCalDmax
 

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Minn-Kota said:
problemchild said:
I went 1 step more. I took the bulbs out of the fog lights and replaced them with 9005 bright lights (high beams) bulbs. When I flip the high beams on its like a 747 landing lights came on in front of my truck.

Yeeee Hawwww............

BRIGHT

Better watch for meltdown of the foglight housings......

It has been a while since I looked, but I believe the foglight bulbs are rated at a little over 20 watts. The 9005 bulbs are rated at about 3 times that amount. So, problemchild, you may want to keep a close watch on the housings.


On edit: Bubz, where did you get that schematic? It is a little difficult to read. Could you possibly email it to me? My address is in my sig. I have been thinking of wiring something up myself, but had no schematic to go by and hate to have to chase down/ring out wires for a few hours.Edited by: flhrciblueice
 

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flhrciblueice -


If you click on the schematic it will open in another window full sized.


Those electrical schematics are handy. It would definitely be nice in troubleshooting and making modifications to the existing system. I too would like to know where a person can get those.
 

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Minn-Kota said:
flhrciblueice -


If you click on the schematic it will open in another window full sized.


Those electrical schematics are handy. It would definitely be nice in troubleshooting and making modifications to the existing system. I too would like to know where a person can get those.

Yeah, I did that, but now I have to figure out how to get it to print. It is so large that I only get about 1/4 - 1/3 of the drawing when I go to print it out. Still working on it.
 

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CntrlCalDmax said:
I'm not sure, but I think the point bubz was making was not to the relay control grounds but rather to both lamps on each side share a common ground. Therefore if the ground is designed to carry the current of one lamp at a time, when you add the other lamp and run both at the same time, you may be overloading the common ground. One would need to know the wattage or current draw of each lamp and the current carrying capability of the common ground to determine for sure.


BTW, the $135 harnesses eliminate this problem by supplying separate grounds for each lamp.
EXACTLY! This, along with the MUCH heavier guage wire harness is
why I would recommend the Caspers Electronics
harness. The "all on" (DRL, fog, highs,etc) mod listed
is just "icing on the cake" to me - so to speak....

I've got the CE harness AND done the diode mods. It's
MUCH brighter now.... :)

Just a FWIW, IMHO, YMMV (etc.. etc..)

T.
 

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All that high power wattage sounds like it would really be appreciated by other drivers. They're fog lights for goodness sake.


Better make sure the wires are all rated to handle that extra current.


- Problemchild, when do you plan to finish designing a better truck from the ground up?


Another dumb*** engineer.
 

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Ask MAC about putting brighter lights in the fog lamp housings!
 

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Better to get some brighter ones like mac did and wire them with the highs. I am not sure why they even bother with the stock fog lights. Mine never did any good in fog or blizzards. As far as I can tell all they do is blind oncoming traffic. Seems like every ugly little suv thing has foglights aimed up about window level to oncoming traffic. The yellow/orange ones are especially bad. They would be better if they were only on with the highs because then they couldn't do that. (Well unless they don't bother to dim) Either way the snowdrifts took care of my foglights... They aren't mounted in there all that solid I guess.
 

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The stock foglight bulbs are 9145's. The rating on the bulb is 43 watts (at least on the ones in my 2003). So going to 9005's is a 50% increase in watts/heat.


I did find that my fogs were adjusted WAAAYYYYY too high from the factory - after adjusting them down to match the lowbeam pattern, they do a much better job. Still thinking of upgrading to 9005's, though........
 

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'nutha stoopudasse engineer here..


I'm too lazy to go look for it, but isn't there some kind of law whereby if you have the "747 landing lights" the cops can pull you over?


Not that I'm really worried about it, just wondering. Anyone know?


Thanks, Mat
 

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Discussion Starter #20
Wow the engineers are very sensitive people. Ive always found that people get the the most whimperish when you get close to home. I worked with a group of engineers when I ran the fiber optic communication lines for the Santa Barbara water pipeline. They were constantly taking things upon themselves (deviating from the paperwork'ed specs)and making changes or just not doing things they were supposed to do.

One of the most memorable was when a specific control unit was called for and they used one they liked instead. 5 million gallons of water dumped out of a water tank and went down the drain (or formed its own mini-river). Another time they were supposed to spec an x feet high, high gain communication tower. Instead they made it x feet shorter. Needless to say the radios didnt work in that valley.

I could go on and on about what I saw on that 1 job alone. It may be just human nature to f things up.

But If I were desiging a truck I wouldnt make intentional mistakes. My 01 silverado had bad pistons. So did the 99,02,03,04. Why make them bad every year?

The duramax injectors require a 2 micron filter at 100%. Instead we get a 44% at 15 microns or whatever it is. The roof on my truck pops and buckles at freeway speeds (WTF?). I would have put rain gutter indents in the metal to give more support. The door chime is deafening loud. The headlights get dim and shut off when I need more light. The seats are convex and push your back out of whack. The headliner rubs and makes noise. The tires are too small. The oils are all a quart or 2 low from the factory. On and on and on. It never ends. Some companies learn from their mistakes, I know I do. But not gmc.
 
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