The secondary air injection (AIR) 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.

DTC P0418

The ECM detects the AIR pump relay control circuit is open. The condition exists for 4 seconds or a cumulative of 30 seconds.

DTC P2444

The ECM detects the AIR pump relay control circuit is shorted to voltage. The condition exists for 4 seconds or a cumulative of 30 seconds.

DTC P2445

The ECM detects the AIR pump relay control circuit is shorted to ground. The condition exists for 4 seconds or a cumulative of 30 seconds.

DTC P0418, P2444, and P2445 are Type B DTCs.

DTC P0418, P2444, and P2445 are Type B DTCs.

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Secondary Air Injection System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, command the Secondary Air Injection Pump Relay ON and OFF with a scan tool. You should hear an audible click.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the KR25 secondary air injection pump relay.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 86 and ground.

⇒	If 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 voltage circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.

3. Connect a test lamp between the control circuit terminal 85 and the ignition circuit terminal 86.
4. 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.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

5. Test for 2.6-4.6 V between the control circuit terminal 85 and ground.

⇒	If the voltage is not within the specified range, replace the K20 ECM.

6. If all circuits test normal, test or replace the KR25 secondary air injection pump relay.

Relay Test

1. Ignition OFF, disconnect the KR25 secondary air injection pump relay.
2. Test for 70-110 Ω between terminals 85 and 86.

⇒	If 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:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the KR25 secondary air injection pump relay.

4. Install a 20 A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than the specified range, replace the KR25 secondary air injection pump relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming