2010 Cadillac CTS Sedan AWD V6-3.6L Page 1221
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P258A
- Vacuum Pump Relay Control Circuit
DTC P258B
- Vacuum Pump Performance
DTC P258C
- Vacuum Pump Relay Control Circuit Low Voltage
DTC P258D
- Vacuum Pump Relay Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) monitors the control circuit of the brake booster pump relay. The ECM supplies ground through the pump relay
control circuit which then supplies B+ voltage to actuate the brake booster pump. B+ voltage is supplied at all times to the coil side of the pump
relay.
Conditions for Running the DTC
P258A, P258C, P258D
Ignition ON.
P258B
* Engine Running
* Vacuum pump is activated for greater than 1.6 seconds.
Conditions for Setting the DTC
P258A, P258C
The ECM detects an open/high resistance on the relay coil control circuit.
P258B
The ECM detects an excessive difference in vacuum levels between the power brake booster and the manifold absolute pressure (MAP).
P258D
The ECM detects a short to voltage on the relay control circuit.
Action Taken When the DTC Sets
DTC P258A, P258B, P258C, P258D are Type B DTCs.
Conditions for Clearing the DTC
DTC P258A, P258B, P258C, P258D are Type B DTCs.
Reference Information
Schematic Reference
Hydraulic Brake Schematics (See: Brakes and Traction Control/Hydraulic System/Diagrams/Electrical Diagrams)
