LED BRAKE LAMPS

CASTLEDFW15

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Good morning all….

Has anyone tried changing 2021 Tahoe rear brake lamps to LED?

I think I got it but still would prefer to get a harness that already has resistors built in.

I did some continuity/voltage checks and also while I am here want to verify.

There are three wires in the OEM wiring harness. I narrowed two of them as power and ground.

Confirm please the wiring diagram.

Yellow………………..Power

Black -#1…..(outer)…….aground/earth etc RGB

Black #2……….That is the mystery wire…..Normally I would think parking and or turn signal but the turn signal/hazard flasher is on a separate bulb, socket and harness……. Any idea what this wire is for…………..

With that out of the way let’s go on to the thread header subject…..

I have upgraded the turn signals to LED (LASFIT) and plug and play…..will give a check turn signal message if operated too long….traffic light etc…. Bulbs fit and intensity is well above OEM incandescent bulbs but not blinding.

Same company offered 921 (Backup lights) but not recommended or at least plan on installing a resistor to avoid the CANBUS error message…..(Check Reverse Lamps). Will clear after a few minutes in drive or you can manually cancel the message with the scroll wheel. Resistors needed to avoid message, but bulb falls out of the lens housing….yes lost and bulb gets stuck in the lens housing. Took a while but I got it out. Refund issued by LASFIT and didn’t require return. Bulbs work and are bright but again have to clear the message. I am thinking resistor will or at least should remove the error message.

I noticed and tried a set just to see if it can be done. There is a 7440 wiring harness that is plug and play for the bulb and socket side. The harness has a interface upstream of the bulb side.

My question is………….

How far upstream is the interface connector? Even if for some reason The OEM brake light harness needed to be replaced how much work is it and what access panes may need to be removed? By panels I am referring to fender well inside and or bumper cap.

If removing the OEM harness and just plugging the LED harness with resistors not only provided but instead so literally plug the bulb to the socket and the upstream end of the wiring harness into the interface I would prefer that option.

To summarize………two major questions.

1…..what is the third (middle) wire used for?

2……. Has anyone removed and replaced the OEM brake light wiring harness and how difficult is it as in where is the upstream connection located?

Thanks all…….oh wait a minute…Texas………..y’all!!!
 

Big Mama

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I can’t help with this but welcome to the forum from Virginia. I’m surprised they don’t have LED standard.
 

CASTLEDFW15

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Your not the only one. …LED standard.

LED running lamps, headlight and presumably Fog Ligjts if they were available for 2021.

What part of VA? NOVA or elsewhere?
 

CASTLEDFW15

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Photos later bug I found some that work and both are brighter than stock without being blinding and no CANBUS ERROR messag. The kits I used are both ALLA. Amazon vendor, Resistors required but not as difficukt as I thought. I even tried some new colder/seal connectors. They have the solder built into the center and glue to help the heat shrink for waterproffing. As you melt the solder it forms around the wiring and the colored bands contain the glue to adhere to the insulation. Easy to identify with the color coded bands. If your not good at T Taps and are not afraid to cut four wires each side (POS/NEG for brake and reverse). The solder/seal connectors should work fine. mine didnt look as good as the video.…they never do right? but still effective. Since my first time using and didnt want to risk it I still went with heat shrink. I have four layers of protection, six counting the wire loom and aluminum foil. Wire, insulation, solder seal, heat shring, electrical tape, wiring loom and aluminum foil…back to the aluminum in a bit. Concept is pretty easy to understand, application takes a bit.

Remove tail light lens assemblies……make it easy on yourself disconnect all four connectors and set lens assembly out of the way.

Use multimeter to find positive and ground wire for the tail lamp. If you are thinking the white and the outer black wire…Correct…but again verify with multimeter.

Same step for brake light and again verify with multimeter but yellow (POS) and outer Black (NEG)

Splice the resistor into one of the POS and NEG wires of each light. Doesnt matter what side of the resistor plugs into as long as the POS and NEG for each light are spliced correctly.

Cut the OEM Harness at the POS/NEG wires, there should be one more (middle black) that does not get cut.

NOTE: Ensure you leave enough wire near the socket to cut, strip, solder and apply connector without getting too close to the socket. You also want enough slack in the resistor to connect to the frame without stretching too far.
For my secnario I applied the S/S connector, heat shrink first after the cut…make sure it doesnt fall too far down the harness…besdt method is to either tape in place or thread to the socket side so it doesnt slide back further.

Apply S&S connector in accordance with manufacturers instructions and if still unsure about water tight connection apply heat shring over connector. Next step is optional but with my first time using this connector and me being challenged with soldering I used small wrap of electrical tape over the shrink wrap…..after it cools of course.

I applied the plastic wiring loom, in my case I just got new portions and taped them around the wires.

You are probably going to have to test fit the resistors in a couple of spots, Mine would up being the portion of the frame immediately adjacent to the lens housing guide pins….near the outer portion of the frame upper and lower. After a test fir or two that should give you a idea of where to mount the resistors.

This step might get some people query but done carefully it would be a clean puncture.

Test fir the resistors and mark the frame where the two mounting holes are on the resisto…..upper/lower resistor. Most people use a punch or a small pilot hole with the smallest drill bit available. I used #4 or #6 1 inch self tapping. Note the head if the screw. Too wide and it will scrape on the resistor body and too narrow it wont have the strength to hold. Also note the pilot hole…..you want the smallest hole available. Definitely at or slightly smaller than the diameter of the screw threads. Too wide and the screw will self tap itself rIshtar through the metal and you have to make a new hole.

Apply wiring loom to protect the wires and tape accordingly.

This step is optional but recommended due to heat.

Fold a sheet of aluminum foil either double or even triple fold and apply over the wiring looms. I did not do the entire harness area just the wiring loom immediately surrounding the resistor, helpe prevent the wiring loom and ultimately the wires themselves from getting hot and melted from the resistor,

Prior to finall installation of the resistor I applied four washers between the frame and the bottom of the resistor. Basically mada a pocket for air to circulate underneath the resistor to help with heat dissipation.

Check function of the brake lamps. Easiest way for me at least was to tape the harness to the side of the body with lens facing out and apply brake pedal. Since these bulbs are LED they are polarity sensitive. If bulb doesn’t work. Don’t panic. Remove and turn 180 degrees and reinstall. Yes the bulb operation needs to be checked but the main focus is to apply brake pedal to ensure there is no “Check Brake lamp” message in the DIC. Leave pedal applied and test pedal with a few applications. If your going to get the error message you should get it fairly quickly. If resistor is not installed correctly the bulbs could work but still get the error message. Unless you have a helper it is best to check the bullbs one at a time using the method of applying the pedal and taping the bulb to the outer frame. For passenger side. Note folding mirror down can help you see it better especially in daylight. I have a shop light on the passenger side so I turned that off to help filter out excess light.

Apply the aluminum foil around the wiring looms immediately surrounding the resistor. Remember is should already be double, triple or even Quadra foiled so a wrap around the loom maybe two0three wraps should be more than fine.

Install bulbs back into the housing, Remember leave enough slack in the resistor to be able to stretch the wires into the housing. Re install the lans assembly with the upper and lower screws. Final step is to reinstall the trim panels for the lens housing.
 

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