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
Disconnect the electrical connector: G18 High Pressure Fuel Pump
Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2
Ignition - On / Vehicle - In Service Mode
Perform the scan tool control function: Fuel Pressure Regulator - On and Off
Verify the test lamp turns On and Off.
- If the test lamp does not turn On and Off
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector: X3 @ K20 Engine Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ 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 infinite resistance between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ Component harness & Ground
7. Test for infinite resistance between the test points:
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
8. Test for less than 2 ohms between the test points:
  - Control circuit terminal 1 @ Component harness & Terminal 16 @ Control module harness
  - Control circuit terminal 2 @ Component harness & Terminal 32 @ 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 the test lamp turns On and Off
Test or replace the component: G18 High Pressure Fuel Pump