P023C - Charge Air Cooler Coolant Pump Control Circuit Low
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
The P023C diagnostic trouble code (DTC) indicates that the Engine Control Unit (ECU) has detected a low voltage condition in the control circuit of the Charge Air Cooler (CAC) coolant pump. This electrical pump circulates coolant through a dedicated radiator and the intercooler to reduce intake air temperatures. The ECU monitors the circuit for feedback; if the voltage remains below a specific threshold when the pump is commanded on, typically due to a short to ground or an internal short in the pump motor, P023C is stored. This often results in reduced engine power to prevent damage from high Intake Air Temperatures (IAT).
Possible Causes
Defective electric coolant pump (internal short circuit)
Short to ground in the wiring harness between pump and ECU
Faulty charge air cooler pump relay (if applicable)
Internal Engine Control Unit (ECU) failure
Symptoms
Recommended Solution
- Visual Inspection: Check the electric coolant pump connector for corrosion or heat damage. Inspect the wiring harness for chafing against the chassis.
- Fuse and Relay Test: Check the fuse dedicated to the CAC cooling system. A blown fuse often indicates a shorted pump.
- Electrical Testing: Disconnect the pump and measure resistance (Ohms) across the pump terminals. A value near 0 Ohms indicates a short. Check for battery voltage (12.6V) at the power terminal and verify the PWM control signal from the ECU.
- Advanced Diagnosis: Use a diagnostic tool to command the pump ON/OFF. Monitor voltage drop during activation.
- Replacement: If the pump has an internal short or draws excessive current, replace the electric CAC coolant pump.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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