2000 chevy blazer will not shut off if u hold the brake pedle down, and through your keys across the street and it stays runin,dash lights and indacaters and guages do not come on. only head lights and brake lights,unhooked brake switch and truck works right.replaced switch still still does it,checked all relays under hood and dash and fuses all good,pulled them all out still does it with no realys pluged in and pedle down.removed dash and inspected harness found no damaged wires or connections traced problem to body harness motor harness and realys are correct when vechle runin brake lights stay on with all unpluged only thing i can think of is body control modual is defective.any ideas?

 

BCM shouldn't have anything to do with the operation of the engine. Sounds like power is back feeding into the ignition circuit from the brake circuit somehow. The circuit that I would inspect is the IGN 1 circuit (CKT 3) in the ignition switch harness (large pink wire). The brake switch output (smaller white wire CKT 17) runs up to the multifunction switch in the steering column. I would inspect the wiring inside the column for signs of wear. You may have to take off the wiring loom to then separate each wire.

Are there any aftermarket electronics on the vehicle (remote starter, etc)?