Could be yer brake fluid sensor on top of the master cylinder. My brake light kept coming on but dim and not consistent all the time...and my fluid was topped up, too!

Since I check my brake fluid all the time...I just unplugged the sensor. <img src="/forums/images/graemlins/wink.gif" alt="" />

1998 T-100 Xtra cab SR5 2WD Auto; Roadmaster Active Suspension; Yokohama Geolander HT-S; lowered air dam; full belly pan; 4? diffuser; 11" side skirts; dual transmission coolers; 67% grill blocked; Auto-RX'd; ScanGauge II/Ultra-Gauge