Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

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.

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: Low Reference circuit terminal 3 & Ground
- If 5 ohms or greater
1. Disconnect the electrical connector: K20 Engine Control Module
2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 3 @ 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 less than 5 ohms
Ignition - On / Vehicle - In Service Mode
Test for 4. 8 to 5. 2 V between the test points: 5 V Reference circuit terminal 2 & Low Reference circuit terminal 3
- If less than 4. 8 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K20 Engine Control Module
3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 2 @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
4. Test for less than 2 ohms between the test points: 5 V Reference circuit terminal 2 @ 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
- If greater than 5. 2 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K20 Engine Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 2 @ 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
- Go to next step: If between 4. 8 and 5. 2 V
Verify the scan tool parameter: BARO = Greater than 4. 7 V
- If 4. 7 V or less
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K20 Engine Control Module
3. Test for infinite resistance between the test points: Signal circuit terminal 4 @ 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 greater than 4. 7 V
Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 4 & Low Reference circuit terminal 3
Verify the scan tool parameter: BARO = Less than 0. 2 V
- If 0. 2 V or greater
1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
2. Disconnect the 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 4 @ 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
5. Ignition/Vehicle - Off
6. Test for less than 2 ohms between the test points: Signal circuit terminal 4 @ 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 less than 0. 2 V
Test or replace the component: B75C Multifunction Intake Air Sensor