2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1918
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B157 secondary air injection pressure sensor.
2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm
between the low reference circuit terminal 2 and ground.
瀚慖f greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20
ECM.
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 Secondary Air Injection Pressure Sensor voltage parameter is less than 0.5 V.
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 Secondary
Air Injection Pressure Sensor voltage parameter is greater than 4.8 V.
瀚慖f less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the
K20 ECM.
6. If all circuits test normal, test or replace the B157 secondary air injection pressure sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Secondary Injection Shutoff Valve Pressure Sensor Replacement (See: Powertrain Management/Emission Control Systems/Air Injection/Air
Injection Check Valve/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P2500
DTC P2500 or P2501
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 P2500
- Generator L-Terminal Circuit Low Voltage
DTC P2501
- Generator L-Terminal Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) uses the generator turn on control circuit, or L-terminal circuit, to control the load of the generator on the engine.
