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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 113 (Engine Controls And Fuel - 4.3L (LV1) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P135A or P135B >> Circuit/System Testing

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.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: X1 @ K20 Engine Control Module
  3. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 72 & Ground
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points:
    • Ignition circuit terminal 62 & Ground
    • Ignition circuit terminal 67 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points:
      • Ignition circuit terminal 62 @ Control module harness & Output terminal @ Fuse
      • Ignition circuit terminal 67 @ Control module harness & Output terminal @ Fuse
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off
    2. Replace the component: Fuse
    3. Ignition - On / Vehicle - In Service Mode
    4. Verify the fuse does not open.
      • If the fuse opens and there are components connected to the circuit - Disconnect a component and repeat procedure starting at step 5. 1
      • If the fuse opens with all components disconnected from the circuit - Repair the short to ground on the circuit.
      • If the fuse does not open after disconnecting a component from the circuit - Replace the component disconnected last.
      • Go to next step: If the fuse does not open with all components connected, except the following component: K20 Engine Control Module
    5. Ignition/Vehicle - Off
    6. Connect the electrical connector: K20 Engine Control Module
    7. Replace the component: Fuse
    8. Ignition - On / Vehicle - In Service Mode
    9. Verify the fuse does not open.
      • If the fuse is open - Replace the component: K20 Engine Control Module
      • Go to next step: If the fuse does not open.
    10. Operate each component on the circuit, one at a time. It might be necessary to use scan tool control functions to operate the components.

      Verify the fuse does not open when any of the components are activated.

      • If the fuse opens - Replace the component that caused the fuse to open when activated.
      • Go to next step: If the fuse does not open.
    11. All OK.
    • Go to next step: If the test lamp turns On 
  6. Replace the component: K20 Engine Control Module
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