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How to Divorce Your DRL Function From Your Low Beams and Make Them Separate Functions

Husker6.5

135' diagonal 16:9HD, 25KW sound!
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This will work on any '96+ CMT 800 series GM with DRL Low Beams.

I just did a DRL bypass on my '98 Suburban so that I could run 50W 5000K HID H1 projector Low Beams on the headlight switch only, while letting separate Hi Intensity LEDS act as as my DRL's.

It was fairly easy to do once you study the factory service manual wiring diagram. The hardest part is accessing the two 7mm head bolts on the firewall located about 4" below and to the left of the Hydroboost unit at 7 and 2 o'clock approximately.

They are a bugger to access with the main wiring harness and Hydroboost plumbing being of course in the way. A 1/4" drive deep 7mm socket with a 3" and 6" extension, a universal joint and 1/4 ratchet are quite handy for snaking into the bolt heads.

Loosen these two bolts and back them out about 3/8", then to take loose the Convenience Center, lay under the dash and by the Emergency Brake bracket, take two thin, long flat blade screwdrivers and at the 4 and 10 o'clock position mounting legs of the Convenience Center reach in and release the lock tabs simultaneously and gently pull the unit forward until the bolts on the other side are against the firewall, then go back to the engine compartment and carefully back the two bolts out another 1/4" until they're unthreaded from the Convenience Center mounting legs, leaving the bolts held in place by the Firewall insulator.

Go back under the dash, grab the Convenience Center and pull 3-4" towards you and twist it around so you can access the wiring on the back. Go to the DRL relay position in the center of the bottom two rows of female spade lugs in the back of the Convenience Center.

There is a TAN wire that comes from the diode power feed of the DRL relay that is hot when the ignition switch is in the On or Run position and goes to the Low Beams.

Cut this TAN wire so you leave an 1"-1 1/2" pigtail on the back of the Convenience Center. Now strip the TAN wire in the HARNESS and crimp on an 18-22ga heat-shrink weatherproof splice to this.

Locate the PURPLE wire coming out of the back of the DRL relay, this comes from the Dash Headlight combination switch and is energized when in the headlight position only.

Cut the PURPLE wire to leave an 1" - 1 1/2" pigtail coming out of the Convenience Center (so you can reverse the modification and go back to factory Low Beam DRL's in the future if needed). Now strip the PURPLE wire in the HARNESS and insert and crimp into the connector you placed on the TAN wire in the HARNESS in the previous step and heat shrink. You have now divorced your Low Beams from the DRL function so they will work only when the dash switch is in the Headlight position.

Next, run an 18ga wire through the firewall plug adjacent to the main wiring harness pass through (it'll enter the compartment slightly above the brake pedal pivot) and run it over to the back of the Convenience Center making sure it it secured and not able to be pinched in any mechanicals or snagged by clumsy feet.

Waterproof heat-shrink crimp splice this wire to the TAN pigtail you made on the back of the Convenience Center. This is now your lead for your new after market DRLs.

Now carefully rotate the Convenience Center back around and align the four legs with the firewall mounting pads but DO NOT click the legs into the retainers.

Go back to the Engine compartment and carefully thread the 7 mm head bolts back into the legs of the Convenience Center and start them about 1/4". This will keep the bolts from being pushed out of the firewall and lost into the Mechanic's Black Hole of "Where the f*ck did those things fall to?"

Now go back under the dash and snap the legs into the firewall mounts until they "click" into place.

Return to the engine compartment and tighten the 7mm bolts down the last 3/8" to 13 lb/in or until just snug against the firewall.

Route the end of the 18ga wire you ran in the engine compartment to your new, divorced DRL's. You can use two standard 55W Halogen driving or fog lamps on a relay, Hi Intensity LEDs, whatever, since this feed was what powered both of the 55W Halogen Low Beams in DRL mode at full battery voltage originally.

Congratulations, I now pronounce you divorced of your Low Beam DRL's!!

Total time: Approx. 2 hours plus mounting time for your new DRL's.
 
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