Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Chevrolet >> 2012 >> Volt >> Repair and Diagnosis >> External Pages >> Different car >> Section 2 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0597-P0599 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the B34A engine coolant thermostat heater.
  2. Service Mode active, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition circuit and replace as necessary.
  3. Command the engine coolant thermostat heater to 10 percent with a scan tool. Test for 2.5-3.5 V between the control circuit terminal 1 and ground.
    • If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
    • If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  4. Command the engine coolant thermostat heater to 100 percent with a scan tool. The DMM should transition from 2.5-3.5 V when commanded to 10 percent to less than 0.1 V when commanded to 100 percent.
    • If the circuit voltage does not correspond to the specified values, replace the K20 ECM.
  5. If all circuits test normal, test or replace the engine coolant thermostat heater.
scientia non olet · About Mike's Workshop Manuals