I installed a pair of 3157 LEDs last night for my DRL (getting the headlamp assembly out was a pain now I have to deal with it again).

I did not have a way of testing them out in the garage last night because of the sensors, DRL won't come on anymore. So this morning I got out and started the car, only to find out passenger side was not working.

1. Could be a defective bulb but could this be an indication that I need a resistor?

2. What is an indicator of a need for resistors?

3. Might be a silly question but does it matter which way the bulb plugs into the socket? I ask because this was an issue with my wife's MB ML63 when I changed the city lights.

4. Is there a way to activate the DRL manually so I can test even at night time?

 

DRL's and LED's from my understanding have never worked well due to the pulsed voltage that GM uses....
Yes the LED's do need to go in correctly polarity wise
your parking brake may need to be off for the DRL's to work.

knowing the year model of your vehicle may help someone answer your question better...

 

Why is it pulsed, is there a purpose for that?

My parking brake was off. I may be wrong but it seems to me that there is a light sensor in the Tahoe that tells it to activate the headlight instead of the DRL at night. I will be taking apart the passenger side headlamp again tonight - I wish there was a way to activate the DRL manually so I wont have to wait until the next morning to see if it's working.

Thanks for the quick response. I should've indicated the model - 2007 Tahoe LT

Thanks!!!

 

the solar sensor on the dash is the sensor, shinning a bright light at it should activate or de-actiave the headlights thou it will have a small delay...

 

Perform a search of the forum under the Tahoe section as I believe MDTAHOE installed LED's in his 07 and he may have listed numbers and some helpful tips..

 

The aforementioned sensor is the hemispherical dome at the front center of the dash pad just under the W/S.