Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. 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
- B22 Brake Pedal Position Sensor
- B23A Camshaft Position Sensor - Bank 1 Exhaust
- B23B Camshaft Position Sensor - Bank 1 Intake
- B23C Camshaft Position Sensor - Bank 2 Exhaust
- B23D Camshaft Position Sensor - Bank 2 Intake
- B37B Engine Oil Pressure Sensor
- B74 Manifold Absolute Pressure Sensor
P0651
- { MG9 } B25B Clutch Pedal Position Sensor
- B26 Crankshaft Position Sensor
- B111B Turbocharger/Supercharger Boost Pressure and Intake Air Temperature Sensor
- { MG9 } B115 Vehicle Speed Sensor
- { MG9 } B287 Shift Fork Position Sensor
- B310 Fuel Pressure and Temperature Sensor
P0697
- 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: Sensor Reference Circuit Status = Malfunction - For the circuit that set the DTC.
- 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 1 @ B1 A/C Refrigerant Pressure Sensor & Ground
- 5 V Reference circuit terminal 6 @ B22 Brake Pedal Position Sensor & Ground
- 5 V Reference circuit terminal 3 @ B23A Camshaft Position Sensor - Bank 1 Exhaust & Ground
- 5 V Reference circuit terminal 3 @ B23B Camshaft Position Sensor - Bank 1 Intake & Ground
- 5 V Reference circuit terminal 3 @ B23C Camshaft Position Sensor - Bank 2 Exhaust & Ground
- 5 V Reference circuit terminal 3 @ B23D Camshaft Position Sensor - Bank 2 Intake & Ground
- 5 V Reference circuit terminal 3 @ B37B Engine Oil Pressure Sensor & Ground
- 5 V Reference circuit terminal 1 @ B74 Manifold Absolute Pressure Sensor & Ground
P0651 - 5V Reference 2 Circuit
- 5 V Reference circuit terminal A @ B25B Clutch Pedal Position Sensor & Ground
- 5 V Reference circuit terminal 3 @ B26 Crankshaft Position Sensor & Ground
- 5 V Reference circuit terminal A @ B111B Turbocharger Boost/Intake Air Temperature Sensor & Ground
- 5 V Reference circuit terminal 1 @ B287 Shift Fork Position Sensor & Ground
- 5 V Reference circuit terminal 1 @ B310 Fuel Pressure and Temperature Sensor & Ground
P0697 - 5V Reference 3 Circuit
- 5 V Reference circuit terminal 1 @ B107 Accelerator Pedal Position Sensor - Sensor 2 & Ground
P06A3 - 5V Reference 4 Circuit
- 5 V Reference circuit terminal 6 @ B107 Accelerator Pedal Position Sensor - Sensor 1 & Ground
- 5 V Reference circuit terminal 5 @ Q38 Throttle Body & Ground
- 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:
  P0641
  - 5 V Reference circuit terminal 9 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 23 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 41 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 57 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 59 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 61 X2 @ Control module harness & Ground
  P0651
  - 5 V Reference circuit terminal 25 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 39 X2 @ Control module harness & Ground
  P0697
  - 5 V Reference circuit terminal 45 X1 @ Control module harness & Ground
  P06A3
  - 5 V Reference circuit terminal 38 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 55 X4 @ 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 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
  - 5 V Reference circuit terminal 9 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 23 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 41 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 57 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 59 X2 @ Control module harness & Ground
  - 5 V Reference circuit terminal 61 X2 @ Control module harness & Ground
  P0651
  - 5 V Reference circuit terminal 25 X4 @ Control module harness & Ground
  - 5 V Reference circuit terminal 39 X2 @ Control module harness & Ground
  P0697
  - 5 V Reference circuit terminal 45 X1 @ Control module harness & Ground
  P06A3
  - 5 V Reference circuit terminal 38 X1 @ Control module harness & Ground
  - 5 V Reference circuit terminal 55 X4 @ 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.