Changing a front light on the GMT900 trucks.

[RayVoy]

One of my DRLs was out. Checked a number of sources, all suggested different lamps. It looked like a 3157 to me, so I made sure I had one on hand and raised the hood.

Before I started, I had checked the steps required to remove the headlight assembly; more than the old Envoy, but it was a nice afternoon for a small driveway job.

Three bolts (10mm) hold the assembly in place, you could see 2 with the hood open. The 3rd was at the bottom of the assembly. To reach this, the front fender-liner had it come out (I only removed the outside bolts (7mm) and plastic push-pins). A few minutes later, the third bolt is out and the headlight assembly is loose. But would it come out, nope, I could not get the wider backside of the assembly through the hole.

Decided to remove the grill; but, upon inspection, it and the complete bumper are one piece. I removed the 6 bolts (10mm) holding the top of the grill in place. With these bolts out of the way, I could pull the front of the grill out enough to get my hand behind it. With the headlight assembly pulled forward I could just touch the DRL socket with my fingers and turn it to loosen and remove.

It was a 3157. 10 minutes later, it was back together, about 90 min from start to finish.

The design engineer needs to spend after-life eternity changing lamps on this vehicle

 

[Mark20]

I glanced at my Silverado's not too long ago and it wasn't obvious either. Guess I'll have to hit the owner's manual to know for sure.

 

[Sparky]

You would think for something like a headlight or DRL bulb it wouldn't be that hard to make it easy to replace...

 

[christo829]

Guess I won't complain about changing the TB's lights any more. It's annoying to take the grille off, but at least
it's all clips, no bolts.

There are a lot of things that the design engineers should be forced to work on, over and over again, so that
at least they'll never design something that poorly thought out again...not just on our trucks.

It does tend to support my supposition that the engineers don't turn their own wrenches...

Cheers-

Chris

 

[RayVoy]

Well, I had a chance, this afternoon, to look under the hood of a friend's, 2010 Silerado.

On this truck, the bulkhead has material removed to let your hand reach the back of the headlight assembly. A 2010 upgrade I guess.

 

[Irishboy02]

Just be mindful, there were a few years (might be fixed now, im not sure) where the DRL bulbs were labeled as 3156/57. However they would burn out in about 2-3 months and cause the socket to melt and or turn real brittle. Turns out, when manufactured, GM screwd up and managed to send the wrong amount of voltage and never adjusted. Gm placed a recall but it never really made it too public. The 3156/57 was your typical 12v application (12-13v operating) however, when running these sockets were actually seeing upwards of 14.5v direct. The proper bulb needed are actually the 4114 bulb to not have any issues. Im going to try and see if i can find this recall article and post it here.

 

[RayVoy]

Almost all automotive lamps use the nominal supply voltage.

The only time the supply voltage is reduced, is when the low beam headlight is used for DRL.

The 3157 is a standard automotive lamp and, as such, is designed to operate on the normal range of voltage from the alternator/battery supply. It should handle all underhood voltage fluctuations just fine.

Now, having said that, I am aware that the 3157 lamp does get very hot (wattage) when left in the "on" state. This heat could have an adverse effect on the lamp socket

 

[Sparky]

My previous car was a 98 camaro, and it used the bright filament for the DRL. It also mounted with the socket above the bulb. 27W of heat was constantly against the socket while the car is on.

Crispy sockets were quite common on those 4th gen Camaros and needed replaced every so often. I replaced both of mine.

 

[RayVoy]

The proper bulb needed are actually the 4114 bulb to not have any issues. .

I just compared the specs on the 3156 and the 4114.

I am not familiar with the 4114, so I had to look it up.

The two bulbs are almost identical.

Both are C-6 configurations, both are rated for 12.8 volts, both are 28.54 watts, both have 4000 hrs operating life, the 3157 is available in amber.

The only difference appears to be the illumination, the 3157 is 302 lumens............. while the 414 is 402 lumens.

The other difference, the 3157 is considered a stop/signal light, the 414 is for use as a driving light.

The advantage of a brighter light is enough for me to buy a set and change the lamp I replaced last month. Thanks for bringing this lamp to my attention Irishboy.


Edit: might also be a good lamp for backup lights.

 

[Blade]

I just compared the specs on the 3156 and the 4114.

I am not familiar with the 4114, so I had to look it up.

The two bulbs are almost identical.

Both are C-6 configurations, both are rated for 12.8 volts, both are 28.54 watts, both have 4000 hrs operating life, the 3157 is available in amber.

The only difference appears to be the illumination, the 3157 is 302 lumens............. while the 414 is 402 lumens.

The other difference, the 3157 is considered a stop/signal light, the 414 is for use as a driving light.

The advantage of a brighter light is enough for me to buy a set and change the lamp I replaced last month. Thanks for bringing this lamp to my attention Irishboy.


Edit: might also be a good lamp for backup lights.

What a great idea!