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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 21 (Engine Controls And Fuel - 4.3L (LV1) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P2635 (Chassis Control Module) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
    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.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector : A7 Fuel Pump and Level Sensor Assembly
  3. 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 38 @ 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 
  4. Connect a test lamp between the test points : Control circuit terminal 1 & Low Reference circuit terminal 2
  5. Ignition - On / Vehicle - In Service Mode
  6. Perform the scan tool control function : Fuel Pump Enable Command @ Engine Control Module - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector : K38 Chassis Control Module
    3. Test for infinite resistance between the test points : Control 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 : Control circuit terminal 1 @ Component harness & Terminal 13 @ 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 the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    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 : Control 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 the test lamp turns On and Off 
  7. Test or replace the component : A7 Fuel Pump and Level Sensor Assembly
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