2010 Cadillac Truck SRX AWD V6-3.0L Page 1487
Circuit/System Testing
1. Ignition OFF, remove the KR25 secondary air injection pump relay.
2. Ignition ON, verify that a test lamp does not illuminate between the controlled output circuit terminal 30 and ground.
瀚慖f the test lamp illuminates, test the controlled output circuit for a short to voltage.
3. Verify that a test lamp illuminates between the secondary air injection pump relay coil B+ circuit terminal 86 and ground.
瀚慖f the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and
the ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
4. Connect a test lamp between the control circuit terminal 85 and the secondary air injection pump relay coil B+ circuit terminal 86.
5. Command the secondary air injection pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing
between the commanded states.
瀚慖f the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control
module.
瀚慖f the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace
the K20 engine control module.
6. If all circuits test normal, test or replace the KR25 secondary air injection pump relay.
Component Testing
1. Ignition OFF, disconnect the KR25 secondary air injection pump relay.
2. Test for 70-110 ohm between terminals 85 and 86.
瀚慖f the resistance is not within the specified range, replace the KR25 secondary air injection pump relay.
3. Test for infinite resistance between the following terminals:
* 86 and 87
* 86 and 30
* 85 and 87
* 87 and 30
瀚慖f not the specified value, replace the KR25 secondary air injection pump relay.
4. Install a 20 A fused jumper wire between relay terminal 86 and B+. Install a jumper wire between relay terminal 85 and ground. Test for less
than 2 ohm between terminals 87 and 30.
瀚慖f greater than the specified range, replace the KR25 secondary air injection pump relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning)for engine control module replacement, setup, and
programming
P0420
DTC P0420 or P0430
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 Descriptor
DTC P0420
- Catalyst System Low Efficiency Bank 1
