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Home >> Chevrolet >> 2020 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 44 (Lighting System - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B258A >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off - Disconnect KR49 Headlamp Low Beam Relay
  2. Connect a test lamp between the test points:Control circuit terminal 86 & Ground
  3. Perform the scan tool control function:Low Beam Lamps - On and Off - Verify the test lamp turns On and Off.
    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off - Disconnect the electrical connector:x5 @ K9 Body Control Module - Ignition - On / Vehicle - In Service Mode
    2. Test for less than 1 V between the test points:Control circuit terminal & Ground - Ignition - On / Vehicle - In Service Mode
      • If 1 V or greater Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    3. Ignition/Vehicle - Off
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:X50A Fuse Block - Underhood
    4. Test for less than 2 ohms between the test points:Control circuit terminal @ Component harness & Control circuit terminal @ Control module harness
      • If 2 ohms or greaterRepair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K9 Body Control Module
    • If the test lamp is always On 
  4. Ignition/Vehicle & All vehicle systems - Off - Disconnect the electrical connector.x5 @ K9 Body Control Module
    1. Replace the component:K9 Body Control Module
    2. Test for infinite resistance between the test points: - B+ & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component:K9 Body Control Module
    • Go to next step: If the test lamp turns On and Off 
  5. Test or replace the component:KR49 Headlamp Low Beam Relay
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