2010 Cadillac CTS Sedan AWD V6-3.6L Page 1219
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)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Brake Booster Vacuum Assist Description and Operation (See: Brakes and Traction Control/Hydraulic System/Description and Operation/Brake
Booster Vacuum Assist Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
1. Verify that a vacuum leak is not present, refer to Brake System Vacuum Source Test (See: Brakes and Traction Control/Hydraulic
System/Testing and Inspection/Component Tests and General Diagnostics/Brake System Vacuum Source Test)
2. Ignition ON, command the relay ON and OFF with a scan tool. Observe to verify that the vacuum relay and motor turns ON and OFF with
each command.
Circuit/System Testing
1. Ignition OFF, disconnect the vacuum pump relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
瀚慖f the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminals listed below and ground.
* Terminal 30
* Terminal 86
瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and
the B+ circuit fuse is open, test or replace the relay.
