2010 Cadillac Truck SRX FWD V6-3.0L Page 2021
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
瀚慖f less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal,
replace the K20 ECM.
瀚慖f greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
4. Verify the scan tool BARO parameter is less than 1 kPa (0.2 psi).
瀚慖f greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 1. Verify the scan tool BARO
parameter is greater than 127 kPa (18.4 psi).
瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace
the K20 ECM.
6. If the circuits test normal, replace the B17 BARO sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Throttle Inlet Absolute Pressure Sensor Replacement (LF1) (See: Powertrain Management/Computers and Control Systems/Absolute
Pressure Sensor/Service and Repair) for BARO sensor replacement
* Control Module References (See: Testing and Inspection/Programming and Relearning) for engine control module replacement, setup, and
programming
P2257
DTC P0418, P2257, or P2258
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* 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 P0418
- Secondary Air Injection Pump Control Circuit
DTC P2257
- Secondary Air Injection Pump Relay Control Circuit Low Voltage
DTC P2258
- Secondary Air Injection Pump Relay Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The secondary air injection system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the
exhaust stream in order to accelerate the catalyst operation. Ignition voltage is supplied directly to the secondary air injection pump relay. The
engine control module (ECM) controls the relay by grounding the control circuit with a solid state device called a driver. The driver is equipped
with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a
voltage by monitoring the feedback voltage.
