Join Date: Sep 2003
Location: Northern VA, USA
The lamp is a dual filament type. One ground two hot leads & one bulb. It sounds like the second hot (brake induced) goes to ground. I believe the brake switch is proving a high resistance to ground, instead of providing a 12 volt supply...or something along those lines. If you have a multimeter, then I would check this out. It is a mechanical part (something like a sliding cylinder) that provides the switching; when you step on the brake pedal.
94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new
88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new