the running light circuit wire is brown. If you are looking in either the front marker lamps or the rear tail lights.
See page 5-63 of the owner's manual.
it means its not charging properly should be 12.6 -14.2 when running.
2002 GMC Sierra daytime running light (DRL) bulb replacement: Purchase the correct replacement daytime running light (DRL) bulb(s) first, before disassembling the vehicle. See sources and related links below for replacement bulb information. Then consult your owner's manual for the daytime running light (DRL) bulb replacement procedure. As simple as it sounds, the owner's manual is the best place to start for bulb replacement instructions and illustrations. You may want to consider replacing both left and right at the same time in order to keep brightness and color equal (optional).
The daytime running light module is found on the front driver of the Ford F 150. It is underneath truck mounted to the front bumper and connected to the wire harness.
The 98 did not come with daytime running lights. It did in Canada and the module is under the left front fender beside the light.
Black. It is actually not black. It is a light tan color. (I have a mounted Black Bear in front of me)
On a 2008 Sierra you must first remove the 2 bolt on top then on the wheel well their is 2 bolt that release the lower front rap around below head light then their is a bolt that must be loosed. the light pulls out from the bottom.
This procedure is probably the same as for a 2007 GMC Sierra, which has been answered here by someone already.
Black. It is actually not black. It is a light tan color. (I have a mounted Black Bear in front of me)
Just in front of the firewall on the right front inner fender. Un-plug it.
Open the hood as the light bulb pop into the back side of the lens
Under the hood on the driver side. Its the only fuse that is a light in color