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.

Ignition/Vehicle - Off

NOTE:

Additional DTCs will set when disconnecting the components.

Disconnect the electrical connector at one of the following components, depending on the DTC that is set:
P0641
- B1 A/C Refrigerant Pressure Sensor
- B23 Camshaft Position Sensor
- B37B Engine Oil Pressure Sensor
- B150 Fuel Tank Pressure Sensor
P0651
- B22 Brake Pedal Position Sensor
- B26 Crankshaft Position Sensor
P0697
- B74 Manifold Absolute Pressure Sensor
- B107 Accelerator Pedal Position Sensor2
P06A3
- B107 Accelerator Pedal Position Sensor1
- Q38 Throttle Body
Ignition - On / Vehicle - In Service Mode
Verify the scan tool parameter: 5V Reference 1-4 Circuit Status = Malfunction
- If not the specified state after disconnecting a component from the circuit
  Test or replace the component: The component that was disconnected last.
- If the specified state and there are components connected to the circuit
  Disconnect a component and repeat step 4.
- Go to next step: If the specified state with all components disconnected from the circuit
Test for 4.8 to 5.2 V between the test points:
P0641 - 5V Reference 1 Circuit
- 5 V Reference circuit terminal 2 @ B1 A/C Refrigerant Pressure Sensor & Ground
P0651 - 5V Reference 2 Circuit
- 5 V Reference circuit terminal 6 @ B22 Brake Pedal Position Sensor & Ground
P0697 - 5V Reference 3 Circuit
- 5 V Reference circuit terminal 1 @ B74 Manifold Absolute Pressure Sensor & Ground
P06A3 - 5V Reference 4 Circuit
- 5 V Reference circuit terminal D @ B107 Accelerator Pedal Position Sensor - Sensor 1 & 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:
  P0641 - 5V Reference 1 Circuit
  - 5 V Reference circuit terminal 26 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 40 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 41 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 43 X3 @ Control module harness & Ground
  P0651 - 5V Reference 2 Circuit
  - 5 V Reference circuit terminal 36 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 38 X3 @ Control module harness & Ground
  P0697 - 5V Reference 3 Circuit
  - 5 V Reference circuit terminal 16 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 28 X3 @ Control module harness & Ground
  P06A3 - 5V Reference 4 Circuit
  - 5 V Reference circuit terminal 24 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 43 X2 @ Control module 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
- 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:
  P0641 - 5V Reference 1 Circuit
  - 5 V Reference circuit terminal 26 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 40 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 41 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 43 X3 @ Control module harness & Ground
  P0651 - 5V Reference 2 Circuit
  - 5 V Reference circuit terminal 36 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 38 X3 @ Control module harness & Ground
  P0697 - 5V Reference 3 Circuit
  - 5 V Reference circuit terminal 16 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 28 X3 @ Control module harness & Ground
  P06A3 - 5V Reference 4 Circuit
  - 5 V Reference circuit terminal 24 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 43 X2 @ Control module 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
All OK.