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:

An empty fuel tank or a defective fuel pump may cause DTCs to set.
If set only as a history DTC, do not replace any component.
Verify the fuel tank is not empty before proceeding.
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: B47 Fuel Pressure Sensor
Test for less than 10 ohms between the test points: Low Reference circuit terminal 2 & Ground
- If 10 ohms or greater
1. Disconnect the electrical connector: K38 Chassis Control Module
2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 2 @ Component harness & Terminal 23 @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K38 Chassis Control Module
- Go to next step: If less than 10 ohms
Ignition - On / Vehicle - In Service Mode
Test for 4. 8 to 5. 2 V between the test points: 5 V Reference circuit terminal 3 & Low Reference circuit terminal 2
- If less than 4. 8 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K38 Chassis Control Module
3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 3 @ 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 3 @ Component harness & Terminal 22 @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K38 Chassis Control Module
- If greater than 5. 2 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K38 Chassis 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 3 @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - If less than 1 V - Replace the component: K38 Chassis Control Module
- Go to next step: If between 4. 8 and 5. 2 V
Verify the scan tool parameter: Fuel Pressure Sensor - Voltage = Less than 1 V
- If 1 V or greater
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K38 Chassis Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: Signal circuit terminal 1 @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - If less than 1 V - Replace the component: K38 Chassis Control Module
- Go to next step: If less than 1 V
Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 1 & 5 V Reference circuit terminal 3
Verify the scan tool parameter: Fuel Pressure Sensor - Voltage = Greater than 4. 8 V
- If 4. 8 V or less
1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
2. Disconnect the electrical connector: K38 Chassis Control Module
3. Test for infinite resistance between the test points: Signal circuit terminal 1 @ 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: Signal circuit terminal 1 @ Component harness & Terminal 10 @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K38 Chassis Control Module
- Go to next step: If greater than 4. 8 V
Test or replace the component: K38 Chassis Control Module