Diagnostic Aids
This code is set to indicate that ABS module caused BRAKE warning light to illuminate. Diagnose accompanying codes first. If BRAKE warning light remains illuminated after ABS fault is corrected, diagnose problems associated with BRAKE warning light (park brake switch, low fluid, etc.). Code 86 should set only with another ABS code. If Code 86 sets alone, replace ABS module.
Suspected intermittents or opens at connectors can be detected with diagnostic service probe which permits voltage to be measured on wires without unplugging connectors. Ensure terminals make good connection. Wiggle wires while running vehicle and watching for codes to set.