P0412
DTC P0412 or P0418
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0412
- Secondary Air Injection (AIR) Solenoid Control Circuit
DTC P0418
- Secondary Air Injection (AIR) Pump Control Circuit
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 and secondary air solenoid valve relay. The engine control module (ECM) controls the relays by grounding the control circuit with a solid state device called a driver. The ECM monitors the control circuits for open, short to ground, or short to voltage conditions.
Conditions for Running the DTC
* The ignition voltage is between 10-32 V.
* The DTCs run continuously once the above conditions are met.
Conditions for Setting the DTC
DTC P0412 or P0418
The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 s.
Action Taken When the DTC Sets
DTC P0412, and P0418 are Type B DTCs.
Conditions for Clearing the DTC
DTC P0412, and P0418 are Type B DTCs.
Diagnostic Aids
If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool AIR Data circuit status parameters. The circuit status parameter changes from OK or Not Run to Fault if there is a condition with the circuit or a connection.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
Description and Operation
Secondary Air Injection System Description Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, command the appropriate relay ON and OFF with a scan tool. You should hear or feel a click and the corresponding secondary air injection component should turn ON and OFF.
2. Command the relay ON and OFF with a scan tool while observing the following corresponding circuit status parameters:
* AIR Pump Relay Ckt Short Gnd Test Status
* AIR Pump Relay Ckt Open Test Status
* AIR Pump Relay Ckt Short Volts Test Status
OR
* AIR Sol Ckt Short Gnd Test Status
* AIR Sol Ckt Open Test Status
* AIR Sol Ckt Short Volts Test Status
Each parameter should toggle between OK and Not Run in response to the commands.
3. 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.
Circuit/System Testing
1. Ignition OFF, remove the appropriate relay.
2. Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal and ground.
• If the test lamp does not illuminate, test the voltage supply 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 voltage supply circuit and replace as necessary.
3. Verify a test lamp does not illuminate between the relay control circuit terminal and 12 V.
• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
4. Test for less than 1 V between the relay coil control circuit terminal and ground.
• If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. Connect a DMM set to the diode setting between the control circuit terminal and ground.
6. Command the relay ON and OFF with a scan tool. The DMM should transition from 2.5-3.5 V when commanded OFF to less than 1 V when commanded ON.
• If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
7. If all circuits test normal, test or replace the relay.
Component Testing
1. Ignition OFF, disconnect the appropriate relay.
2. Test for the following resistance between terminals 85 and 86.
* 50-75 ohms-KR25 secondary air injection pump relay
* 70-110 ohms-KR26 secondary air injection solenoid relay
• If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 86 and 87
* 86 and 30
* 85 and 87
* 87 and 30
• If not the specified value, replace the relay.
4. Install a 15 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 ohms between terminals 87 and 30.
• If greater than the specified range, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for Engine Control Module replacement, setup, and programming