Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P050F: Brake Assist Vacuum To LowCircuit/System Description
The brake booster pressure sensor measures the negative air pressure or vacuum reserve in the brake booster assembly. During engine running conditions, the brake booster pressure sensor signal circuit voltage varies, depending on the vacuum reserve internal to the brake booster. If the brake booster vacuum is to low, a command to turn the engine on will be given.
Conditions for Running the DTC
Condition 1
| • | DTC P0556 is not set. |
| • | The vehicle is in an AutoStop. |
| • | Brake pressure change is less than 30 kPa (4.4 psi). |
| • | Master Cylinder Brake Pressure less than 4000 kPa (580 psi). |
Condition 2
| • | DTC P0556 is not set. |
| • | The vehicle is accelerating with the drivers foot off the brake pedal. |
| • | Engine vacuum is less than 20 kPa. |
| • | MAF sensor greater than 6 g/s. |
| • | Difference in brake booster pressure and engine pressure must be at least 10 kPa (1.5 psi). |
| • | Change in brake pressure is less than 30 kPa (4.4 psi). |
| • | Master cylinder brake pressure is less than 200 kPa (29 psi). |
Conditions for Setting the DTC
Condition 1
A vacuum leak of 0.9 kPa (.13 psi) per second is detected in the brake assist system during an Autostop.
Condition 2
A vacuum leak of 0.65 kPa (.1 psi) per second is present in the brake assist system during acceleration.
Action Taken When the DTC Sets
DTC P050F is a Type B DTC.
Conditions for Clearing the DTC
DTC P050F is a Type B DTC.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Brake Assist System Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Circuit/System Verification
Verify that DTC P0556, P0557, or P0558 is not set.
| ⇒ | If the DTC is set, refer to DTC P0556, P0557, or P0558. |
| ⇒ | If the DTC is not set, refer to Brake Assist System Diagnosis. |
