P0719Brake Switch B Circuit Low
- Generic OBD-II code · Powertrain
- How the car detects it
- Brake switch B is the brake signal to the transmission module or a second brake switch channel, used to release the converter clutch, adapt shift strategy on grades and cancel cruise control. Low and high describe the signal voltage, and what that means depends on polarity: GM's converter clutch brake switch is closed at rest (12 V), while Saab's Trionic 8 sees 12 V when braking. Detection is always a plausibility check against driving: the brake reads applied during accelerations or never applied during decelerations. P0719 means the signal stays low. For GM that reads as brake applied: 2006 transmission modules flag it after eight accelerations without the brake releasing, without MIL. Saab's Trionic 8 flags the brake light signal not changing during four decelerations from 40 to 3 km/h and disables cruise control. The opposite is P0724.
- What you may notice
- Cruise control cannot be activated or switches off
- Unusual shifting, converter clutch behaviour changed
- No downshift on uphill grades (Subaru)
- Brake lights stay off or on
- Likely causes
- LikelyBrake light switch faulty or misadjusted
- PossibleWire to the module open (GM) or shorted to ground (Saab T8)
- PossibleConnector at the pedal box corroded
- RareBrake light circuit fuse blown
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €150
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.