I just installed LED headlights and fog lights in my 2014 GMC Sierra SLE in an attempt to improve the “dome of darkness” OEM headlights. I don’t know if Chevrolet’s headlight arrangement is similar to the GMC’s headlights, but I thought I would mention my experience just in case. I did not replace my turn signals or brake/tail light bulbs because I have battled the computer’s current sensor in the past and it was a pain.
Regarding the headlights, I bought my headlights from Xenon Depot. They have a very good reference on what must be done to make the LED headlights work properly. On GMC trucks that do not have the “signature” LED daytime running lamps, the low beam bulb (or the ONLY bulb on the idiotic GMC design) is used at a reduced voltage for the DRL function. The lower voltage is generated by pulse width modulation (PWM)–basically, the power is turned on and off rapidly so the “average” voltage is about 11 volts for the DRLs. From reading the TSB regarding headlight complaints, it appears that even the normal headlight operating voltage is still a PWM waveform. While the halogen bulbs don’t care about the PWM signal (the filament cannot react quickly enough to see the flickering), the LED bulbs don’t like it at all. Xenon Depot sells a separate “CAN Bus” kit for their headlights that stabilizes the voltage to a constant level that the LED headlights don’t mind. While it is somewhat of a misnomer (the module doesn’t connect to the CAN bus at all), it does fix the headlight flickering problem. When I tried installing an LED headlight bulb without the module, it turned on and off randomly. In summary, if you do not have the signature LED lighting on your truck, you may be fighting the PWM waveform problem.
Just for anyone else considering an LED bulb swap, the LEDs work much better on the low beam setting than the OEM halogen bulbs did (at least on my GMC). Of course, the “veil of blackness” still descends (you can’t fix that poor design with a bulb swap), but you do get some more peripheral lighting. The LED fog light swap made a very big difference in visibility. Unfortunately, on the high beam setting, the LED bulbs don’t have the focused beam offered by the halogen bulbs, so your distance vision is definitely worse. You need to be very careful to install the LED bulbs with the LEDs in the correct position (read the instructions) or you will have a very strange beam pattern.
