Circuit/System Verification

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 ON.
Verify DTC P037E, P037F, P066A-P066F, P0671 - P0674, P067A, or P067B is not set.
- If DTC P037E, P037F, P066A-P066F, P0671 - P0674, P067A, or P067B is set
  Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If a DTC P037E, P037F, P066A-P066F, P0671 - P0674, P067A, or P067B is not set
Ignition ON.
Using a scan tool observe the following parameters.
Verify that NO parameters display Malfunction.
- Cylinder 1, 2, 3, or 4 Glow Plug Control Open Test Status
- Cylinder 1, 2, 3, or 4 Glow Plug Control High Voltage Test Status
- Cylinder 1, 2, 3, or 4 Glow Plug Control Low Voltage Test Status
- If Malfunction is displayed
  Refer to Circuit/System Testing.
- Go to next step: If Malfunction is not displayed
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not set. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
- If a DTC sets
  Refer to Circuit/System Testing.
- Go to next step: If a DTC does not set
All OK.