Code 91: Brake Switch Circuit Open All The Time: Notes
When wheel speed sensors indicate to ABS module that vehicle is braking, ABS module should receive voltage from brake switch. If ABS module does not receive voltage, ABS operation will be disabled and ABS light will illuminate. See Fig 1 .
Code 91 will set if brake switch circuit is open during normal stop. This code can be set during multiple normal (non-ABS) stops.