B3000 SE Regular Cab 2WD V6-3.0L OHV (2002)
Brake Pressure Switch: Technical Service Bulletins
Brakes - Brake Pressure Switch DTC C1939 Addition
Bulletin No: 04-006/02
Last Issued: 12/11/2002
Subject:
BRAKE PRESSURE SWITCH / DEACTIVATOR SWITCH CIRCUIT FAILURE DIAGNOSIS C1939
APPLICABLE MODEL(S)/VINs
All 2001-2003 Truck with 4WABS
DESCRIPTION
DTC C1939 is missing from 2001-2003 workshop manual. C1939 is for an open or short circuit in the Brake Pressure Switch (BPS).
The BPS serves two purposes; first, it is an input to the ABS control module to indicate that pressure exists in the Brake Master Cylinder, second, it is a
back up input to the PCM for cruise control, it indicates the brake pedal has been pressed in addition to the Brake On Off (BOO) switch. (For cruise
control the Brake Pressure Switch is sometimes referred to as the Deactivator Switch).
The BPS is a normally closed switch. It provides a B+ signal to the ABS control module, this switch opens circuit momentarily when the brake pedal is
pressed hard.
