Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
NOTE:
Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
- Verify the following conditions do not exist:
- B75C Multifunction Intake Air Sensor - Contamination of the measuring element/Cracked/Visible Damage/Water intrusion
- Intake Air Duct - Cracked/Incorrect connection/Restricted/Visible Damage
- If a condition exists
Repair or replace as necessary
- Go to next step: If no condition exists
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the electrical connector: B75C Multifunction Intake Air Sensor
- Test for less than 5 ohms between the test points: Ground circuit terminal 7 & Ground
- If 5 ohms or greater
- Disconnect the electrical connector: B75C Multifunction Intake Air Sensor
- Test for less than 5 ohms between the test points: Low Reference circuit terminal 3 & Ground
- If 5 ohms or greater
- Disconnect the appropriate electrical connector: @ K20 Engine Control Module
- Test for less than 2 ohms between the test points: Low Reference circuit terminal 3@Component harness & The other end of the circuit
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K20 Engine Control Module
- Go to next step: If less than 5 ohms
- Ignition - On/Vehicle - In Service Mode
- 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
- Ignition/Vehicle - Off & Remove - Test lamp
- Test for less than 2 ohms between the test points: Ignition circuit terminal 5@Control module harness & Output terminal@Fuse
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - 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
- Ignition/Vehicle - Off
- Replace the component: Fuse
- Ignition - On/Vehicle - In Service Mode
- 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 5.1
- 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.
- Go to next step: If the fuse does not open with all components connected, except the following component: K20 Engine Control Module
- Ignition/Vehicle - Off
- Connect the electrical connector: K20 Engine Control Module
- Replace the component: Fuse
- Ignition - On/Vehicle - In Service Mode
- Verify the fuse does not open.
- If the fuse is open - Replace the component: K20 Engine Control Module
- Go to next step: If the fuse does not open.
- 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.
- Go to next step: If the fuse does not open.
- All OK.
NOTE:It may be necessary to use a scan tool control function to operate a component.
- Go to next step: If the test lamp turns On
- Verify the scan tool parameter: IAT Sensor 1 = Colder than -39°C (-38°F)
- If -39°C (-38°F) or warmer
- Ignition/Vehicle - Off
- Disconnect the appropriate electrical connector: K20 Engine Control Module
- Test for infinite resistance between the test points: Signal circuit terminal 1@Component harness & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: K20 Engine Control Module
- Go to next step: If colder than -39°C (-38°F)
- Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 1 & Low Reference circuit terminal 3
- Verify the scan tool parameter: IAT Sensor 1 = Warmer than 149°C (300°F)
- If 149°C (300°F) or colder
- Ignition/Vehicle - Off & Remove - Jumper wire(s)
- Disconnect the appropriate electrical connector: K20 Engine Control Module
- Ignition - On/Vehicle - In Service Mode
- Test for less than 1 V between the test points: Signal circuit terminal 1@Component harness & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for less than 2 ohms between the test points: Signal circuit terminal 1@Component harness & The other end of the circuit@Control module harness
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K20 Engine Control Module
- Go to next step: If warmer than 149°C (300°F)
- Verify the scan tool parameter: Intake Air Humidity Sensor = Less than 1%
- If 1% or greater
- Ignition/Vehicle - Off
- Disconnect the appropriate electrical connector: K20 Engine Control Module
- Test for infinite resistance between the test points: Signal circuit terminal 8 & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: K20 Engine Control Module
- Go to next step: If less than 1%
- Ignition/Vehicle - Off
- Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 8@Component harness & Low Reference circuit terminal 3
- Ignition - On/Vehicle - In Service Mode
- Verify the scan tool parameter: Intake Air Humidity Sensor = Greater than 99%
- If less than 99%
- Ignition/Vehicle - Off & Remove - Jumper wire(s)
- Disconnect the appropriate electrical connector: K20 Engine Control Module
- Ignition - On/Vehicle - In Service Mode
- Test for less than 1 V between the test points: Signal circuit terminal 8 & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for less than 2 ohms between the test points: Signal circuit terminal 8 & The other end of the circuit
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K20 Engine Control Module
NOTE:Internal control module or component damage may occur if the circuit shorts to B+.
- If greater than 99%
- Test or replace the component: B75C Multifunction Intake Air Sensor