• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

• Engine=Running—Greater than 1 s
• Engine Speed=Greater than 300 RPM
• Ignition Voltage=Greater than 9.1 V

Frequency the DTC runs=Continuously—After the running conditions are met—For greater than 1 s

MAF Sensor=Less than 1,050 Hz—For greater than 2 s

MAF Sensor=Greater than 14,500 Hz—For greater than 2 s

DTCs listed in the DTC Descriptor category=Type A DTC

DTCs listed in the DTC Descriptor category=Type A DTC

Engine Controls Schematics

Master Electrical Component List

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References

1. Engine » Idling — At normal operating temperature
2. Verify the scan tool parameter:MAF Sensor=Parameter Normal Range:1.5 to 3.5 g/s
• If not between 1.5 and 3.5 g/s

  Refer to: Circuit/System Testing

• If between 1.5 and 3.5 g/s
3. Monitor the scan tool parameter:MAF Sensor

   Perform the following steps:

1. Engine»Idling
2. Increase the engine speed slowly to 3 000 RPM and then back to idle.
3. Review Stored Data
4. While reviewing the data frame by frame, the parameter should change smoothly and gradually as the engine speed was increased and decreased.
• If the value does not change smoothly and gradually

  Refer to: Circuit/System Testing

• If the value changes smoothly and gradually
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
5. Verify the DTC does not set.
• If the DTC sets

  Refer to: Circuit/System Testing

• If the DTC does not set
6. All OK.

Note: It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

1. Ignition/Vehicle & All vehicle systems » Off
2. Disconnect the electrical connector:B75C Multifunction Intake Air Sensor
3. Test for less than 5 Ω between the test points:Ground circuit terminal 7&Ground
• If 5 Ω or greater
1. Disconnect the appropriate ground connection:Ground terminal
2. Test for less than 2 Ω between the test points:Ground circuit terminal 7@Component harness&The other end of the circuit@Ground terminal
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Repair the open/high resistance in the ground connection.
• If less than 5 Ω
4. Ignition » On / Vehicle » In Service Mode
5. Verify a test lamp turns On between the test points:Ignition circuit terminal 5&Ground
• If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Test for less than 2 Ω between the test points:Ignition circuit terminal 5&Output terminal@Fuse
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Verify the fuse is OK and there is voltage at the fuse.
• If the test lamp does not turn On and the circuit fuse is open
3. Ignition/Vehicle » Off & Remove » Test lamp
4. Ignition » On / Vehicle » In Service Mode
5. Replace the component:Fuse
6. Verify the fuse does not open.
• If the fuse opens and there are components connected to the circuit » Disconnect a component and repeat procedure starting at step 5.3
• If the fuse opens with all components disconnected from the circuit » Repair the short to ground on the circuit.
• If the fuse does not open after disconnecting a component from the circuit » Replace the component disconnected last.
• If the fuse does not open.

Note: It may be necessary to use a scan tool control function to operate a component.

7. Operate the component:Each component on the circuit—One at a time

Verify the fuse does not open when any of the components are activated.

• If the fuse opens » Replace the component that caused the fuse to open when activated.
• If the fuse does not open.
8. All OK.
• If the test lamp turns On
6. Test for 4.8 to 5.2 V between the test points:Signal circuit terminal 6&Ground
• If less than 4.8 V
1. Ignition/Vehicle » Off
2. Disconnect the appropriate electrical connector:K20 Engine Control Module
3. Test for infinite resistance between the test points:Signal circuit terminal 6@Component harness&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
4. Test for less than 2 Ω between the test points:Signal circuit terminal 6@Component harness&The other end of the circuit@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If greater than 5.2 V
1. Ignition/Vehicle » Off
2. Disconnect the appropriate electrical connector:K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode
4. Test for less than 1 V between the test points:Signal circuit terminal 6@Component harness&Ground
• If 1 V or greater » Repair the short to voltage on the circuit.
• If less than 1 V » Replace the component:K20 Engine Control Module
• If between 4.8 and 5.2 V
7. Test or replace the component:B75C Multifunction Intake Air Sensor

Note: Circuit/System Testing must be performed before proceeding with Component Testing.

1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:B75C Multifunction Intake Air Sensor
3. Install&Setup»EL-38522 - Variable Signal Generator
• Duty Cycle»50%
• Frequency»5,000 Hz
• Voltage»5 V
• Black lead@Ground
• Red lead@Signal circuit terminal 6
4. Engine » Idling
5. Verify the scan tool parameter:MAF Sensor=4 950 to 5 050 Hz
• If not between 4 950 and 5 050 Hz

  Replace the component:K20 Engine Control Module

• If between 4 950 and 5 050 Hz
6. Replace the component:B75C Multifunction Intake Air Sensor

Perform the Diagnostic Repair Verification after completing the repair:Diagnostic Repair Verification

• Mass Airflow Sensor Replacement—B75C Multifunction Intake Air Sensor
• For control module replacement, programming, and setup refer to:Control Module References