Notes On Intermittents
WARNING: This page is about a different car, the 1988 Cadillac Seville and 1988 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
Check brake switch for proper adjustment. Check for intermittent open between fuse No. 7 to brake switch and then from brake switch to ECM. If fuse No. 7 blows intermittently, check for short to ground in circuit Nos. 39 and 420.