Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Theory Of Operation
To improve engine performance the Charge Air Cooler (CAC) system is used to reduce the temperature of the air entering the combustion chambers. The temperature increase of the air entering engine is caused by the Turbocharger. The Low Temp Cooling system consists of an electric Auxiliary Coolant Pump, Charge Air Cooler, Coolant Reservoir, Charge Air Cooler Radiator, Charge Air Cooler Coolant Temperature Sensor and plumbing. The Low Temp Cooling system operates independent of the vehicle's primary cooling system.
The Auxiliary Coolant Pump is a smart device that contains a LIN Bus communication module and a coolant pump. To maintain a desired charge air temperature, the PCM sends a pump speed command over the LIN bus to the Auxiliary Coolant Pump. The internal Auxiliary Coolant Pump module controls the pump speed/coolant flow rate using Pulse-Width Modulation (PWM). The Auxiliary Coolant Pump assembly monitors for internal system circuit and performance failures. If a fault occurs the Auxiliary Coolant Pump module sends the fault information to the PCM through the dedicated LIN Bus. The PCM processes the information received, then sets the correlating fault.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.