DTC P0597: Engine Coolant Thermostat Heater Control Circuit
DTC P0598: Engine Coolant Thermostat Heater Control Circuit Low Voltage
Thats straight from GMs Service Information
DTC P0597: Engine Coolant Thermostat Heater Control Circuit
DTC P0598: Engine Coolant Thermostat Heater Control Circuit Low Voltage
Thats straight from GMs Service Information