Geometry C Cooling System Dual-Loop Diagnosis and Replacement Guide

Fault Background

The Geometry C cooling system covers two circuits: traction battery cooling and e-drive system cooling. There are four components to be cooled: traction battery, e-drive system (motor controller + motor), high/low voltage charging system — the motor rotor spins at high speed, AC/DC conversion, DC/DC low-voltage charging, and battery charge/discharge all generate heat, all dissipated by coolant circulation. The system consists of integrated thermal management module, two electric coolant pumps (battery pump + motor pump, driven by low-voltage circuit), expansion tank, radiator, radiator fan, and active grille shutter motor. Key points: The battery pump is PWM-controlled by the VCU, with different PWM corresponding to different speeds; The cooling fan can be force-driven via the diagnostic scan tool's "actuator function test" for quick diagnosis; The expansion tank coolant level should be between the MIN~MAX marks when cold (thermal expansion/contraction automatically replenishes and bleeds air); The threshold for motor pump circuit diagnosis is open circuit <1Ω, short to ground ≥10kΩ. This article organizes the system composition, working principle, diagnosis, and replacement into a reference guide.

System Composition and Working Principle

Diagnostic Points

Routine checks: ① Check for aftermarket additions that may affect the cooling system; ② Check for obvious damage to easily contacted system components; ③ Check visible cooling system hoses for coolant leaks; ④ Use the diagnostic scan tool's "actuator function test" to force-drive the cooling fan and see if it operates normally—quickly diagnose fan and circuit faults.

Connectors and signals:

• Cooling fan harness connector: fan control signal (cooling fan PWM control signal);
• Battery cooling pump harness connector BV09: battery cooling pump control signal;
• Motor pump harness connector BV14: motor pump control signal.

Motor pump circuit diagnosis (circuit between pump and main A/C relay): Disconnect pump harness connector BV14, use a multimeter to measure BV14 terminal 3—open circuit check standard resistance <1Ω, short to ground check ≥10kΩ, short to power check; if not within spec, repair or replace the harness. For cooling fan inoperative faults, refer to the manual's "Cooling Fan Fault" specific procedure.

Replacement Procedure and Torque

Motor electronic water pump replacement: Remove front compartment trim cover assembly → Remove front underbody splash shield → Drain traction battery coolant → Remove pump fasteners (torque 9N·m) → Remove pump; install in reverse order → Fill traction battery coolant.

Expansion tank assembly (side-mounted) replacement: Remove front compartment trim cover → Drain traction battery coolant → Remove hoses and fasteners → Replace expansion tank → Reinstall → Fill traction battery coolant.

Charger outlet hose replacement: Remove front compartment trim cover → Drain traction battery coolant → Remove front underbody splash shield → Replace outlet hose → Reinstall → Fill traction battery coolant.

Safety Warnings

• This article is for technical reference; cooling system maintenance must be performed by certified personnel per OEM specifications. Readers unfamiliar with the procedure are strictly prohibited from performing it themselves.
• Perform coolant work after the vehicle has cooled to prevent burns; avoid coolant splashing onto high-voltage connectors and harness connectors during draining/filling.
• The coolant level must be between the MIN~MAX marks on the expansion tank when cold; too high or too low affects heat exchange and air bleeding.
• After replacing the pump and hoses, coolant must be filled and leaks checked; road test to confirm the fan and pump operate normally according to coolant temperature.

Maintenance Insights

Three most practical field experiences for the Geometry C cooling system. First, "function test before disassembly"—if you suspect the fan isn't spinning, first use the diagnostic scan tool to force-drive the fan; one actuator test can quickly narrow down whether it's "fan faulty / circuit faulty / control faulty," much faster than disassembling the front bumper. Second, "PWM logic"—the battery pump is PWM-controlled by the VCU, with different PWM corresponding to different speeds; the fan in "motor circuit and battery circuit in series cooling mode" requests speed based on battery inlet temperature—so for "pump not spinning / fan not spinning," first confirm whether the current operating condition actually requires it to spin, rather than immediately judging it as a fault. Third, "three numbers + one level": motor pump circuit open <1Ω, short to ground ≥10kΩ, pump fastener 9N·m; expansion tank cold level MIN~MAX—most complaints of leaks, air locks, and poor thermal management can be answered by the level and these three numbers.

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【This article is for reference only】