Driving Lights vs Headlights - Difference?

[98K1500Utah]

Is there truly a difference between driving (daytime) lights and low beam headlights? On my 98 K1500 I can barely tell a difference. Should there be, and if so, how drastic?

 

[df2x4]

The daytime running light is the low beam. The only difference is when you turn the headlight switch on your tail lights and marker lights come on.

 

[slowburb]

Is it not the case that less juice is fed to the low beams during DRL operation, so they're not as "bright" as when the low beams are lit?

 

[RedLeader289]

Idk about the DRL's on trucks but I know that I couldn't tell a difference on any of the cars I've had that had em.

 

[df2x4]

Is it not the case that less juice is fed to the low beams during DRL operation, so they're not as "bright" as when the low beams are lit?

I don't think so...

I'd go check right now but my multimeter is across town.

 

[slowburb]

Pretty sure the DRL module under the dash is a 2 volt drop diode.

 

[mattillac]

On my 1999 they are different brightness.

I usually use the DRL at night, unless I am on a non lighted roadway etc.

Not a huge difference, enough to notice though.

 

[df2x4]

I wonder if that's something that changed in the 98+ trucks, because I can't tell a difference at all in either of my '97s. If the DRL module does cause a 2V drop then I'd expect a very visible reduction in output, and my trucks show none.

Next time I'm at the shop I'll grab the multimeter and double check but I'm 99% sure there's no difference on the '97s.

EDIT - Forgot that slowburb has a '96, so much for the '98+ theory. Strange...

 

[BowtieBrody]

I could tell a difference in light with my old 97 Burb, it was barely noticeable because of the absolute garbage headlights.
Did the 96's have daytime running lights? My K2500 doesn't have them, neither does my dad's 99 C3500; do the larger trucks come with the DRL already disabled or something?

 

[df2x4]

Now I'm really curious...

I did some Googling and came up with a few other threads where people had mentioned this. The red truck is across town in storage right now (with my multimeter in the toolbox of course), but I went outside and stared at the Suburban's headlights from inside the cab and out with the switch on and off. If anyone saw me they probably thought I was nuts. It looks like there could be a tiny bit of a difference, but it can't be very much. It's so little that I haven't noticed it in either truck during the 10+ years I've been driving them. Then again I haven't really been looking for it until now, either.