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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls And Fuel - 2.0L (LSY) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0030-P0032, P0036-P0038, P0054, P0135, P0141, P103B, or P103C >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

Test 1

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the appropriate electrical connector: B52 Heated Oxygen Sensor
  3. Ignition - On/Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points:
    • {B52A Heated Oxygen Sensor 1} Ignition circuit terminal 5 & Ground
    • {B52B Heated Oxygen Sensor 2} Ignition circuit terminal 2 & 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:
      • {B52A Heated Oxygen Sensor 1} Ignition circuit terminal 5 & Output terminal @ Fuse
      • {B52B Heated Oxygen Sensor 2} Ignition circuit terminal 2 & 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 & Remove - Test lamp
    2. Connect the electrical connector: B52 Heated Oxygen Sensor
    3. Ignition - On/Vehicle - In Service Mode
    4. Replace the component: Fuse
    5. 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 4.4
      • 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.
      6. NOTE:

      It may be necessary to use a scan tool control function to operate a component.

    6. Operate the component: Each component on the circuit - One at a time

      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.
    7. All OK.
    • Go to next step: If the test lamp turns On 
  5. Verify a test lamp does not turn On between the test points:
    • {B52A Heated Oxygen Sensor 1} Ignition circuit terminal 5 & Control circuit terminal 6
    • {B52B Heated Oxygen Sensor 2} Ignition circuit terminal 2 & Control circuit terminal 1
    • If the test lamp turns On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points:
      • {B52A Heated Oxygen Sensor 1} Control circuit terminal 6 @ Component harness & Ground
      • {B52B Heated Oxygen Sensor 2} Control circuit terminal 1 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp does not turn On 
  6. Remove - Test Lamp
  7. Engine - Running
  8. Verify the scan tool parameter: HO2S 1, 2 Heater Control Circuit Open Test Status = Malfunction
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:
      • {B52A Heated Oxygen Sensor 1} Control circuit terminal 6 @ Component harness & Ground
      • {B52B Heated Oxygen Sensor 2} 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: K20 Engine Control Module
    • Go to next step: If the specified value 
    9. NOTE:
    • As little as 10 ohms of resistance in a circuit may cause a DTC to set.
    • Performing this test may set additional DTCs.
  9. Connect a 3 A fused jumper wire between the test points:
    • {B52A Heated Oxygen Sensor 1} Ignition circuit terminal 5 & Control circuit terminal 6
    • {B52B Heated Oxygen Sensor 2} Ignition circuit terminal 2 & Control circuit terminal 1
  10. Engine - Running
  11. Verify the scan tool parameter: HO2S 1, 2 Heater Control Circuit High Voltage Test Status = Malfunction
    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for less than 2 ohms between the test points:
      • {B52A Heated Oxygen Sensor 1} Control circuit terminal 6 @ Component harness & The other end of the circuit @ Control module harness
      • {B52B Heated Oxygen Sensor 2} Control circuit terminal 1 @ Component harness & The other end of the circuit @ 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 specified state 
  12. Test or replace the component: B52 Heated Oxygen Sensor

Test 2

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: X2 @ K20 Engine Control Module
  3. Test circuit 5294 for an open/high resistance between the test points: Ignition circuit terminal 9 X2 @ Control module harness & Output terminal @ Fuse
    • If the circuit is open/high resistance 

      Repair the open/high resistance in the circuit.

    • Go to next step: If the circuit is not open/high resistance 
  4. Replace the component: K20 Engine Control Module
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