This bulletin applies to 2018 Cadillac ATS, CT6 and CTS models equipped with a 2.0L engine. On some vehicles, an electrical connection in the circuit board may fail in the engine control module (ECM). If this occurs, the MIL/Check Engine light may illuminate.
Depending on the specific vehicle’s VIN, the replacement ECM is available as part number 12669908 or 12687467.
After replacing the ECM, ensure that the programming tool is equipped with the latest software and is securely connected to the data link connector to avoid damaging the ECM.
Stable battery voltage is critical during programming. Install the EL-49642 SPS programming support tool. If not available, connect a fully charged 12V jumper or booster pack disconnected from the AC voltage supply. DO NOT connect a battery charger.
Turn off or disable systems that may place a load on the vehicle battery such as interior lights, exterior lights (including daytime running lights), HVAC, radio, etc.
Clear DTCs after programming is complete.