Brake Signal: Description and Operation

Brake On Off Switch:

PURPOSE
Disengages torque converter clutch when brake is applied.

LOCATION
On brake pedal support.

OPERATION
The Brake On/Off (BOO) switch tells the Powertrain Control Module (PCM) when the brakes are applied. The switch closes when the brakes are applied and the switch opens when the brakes are released.

SYMPTOMS
Failed on or not connected - Torque converter clutch will not engage at less than 1/3 throttle.
Failed off - Torque converter clutch will not disengage when brake is applied.

DIAGNOSTIC TROUBLE CODES
74 (two digit), 536 (three digit).