P2CF5

Code

Generic P — Powertrain

Hybrid/EV Battery Pack Coolant Pump B Stuck/Stalled

Brand: Generic

Type: P — Powertrain

Views: UK: 9 EN: 24 RU: 13

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Page language: EN

Causes

Mechanical seizure of pump (impeller jammed with debris or corrosion)
Failed pump motor (winding open/short or internal mechanical failure)
Open or short in pump power supply wiring or connector
Faulty pump driver / inverter module or MOSFET(s) in the controller
Blown fuse or tripped high-voltage relay for pump circuit
Low-voltage supply (12 V) or HV supply fault to pump

Symptoms

Battery thermal management fault warning on dash or reduced battery performance
Cooling system fault message or limited HVAC/charging behavior
No audible pump noise when pump commanded ON
Elevated battery pack temperature or inability to maintain target temperature
Possible diagnostic trouble light (DTC/MIL) illuminated
Reduced charge rate or limp-home mode depending on vehicle strategy

What to check

Record freeze frame and freeze data related to DTC: state of charge, temperatures, command state for Pump B
Visually inspect pump, hoses, connectors, and wiring for damage, corrosion, or disconnection
Check relevant fuses, relays, and HV interlock status for pump circuit
Listen for pump operation when commanded; check for vibration/rotation at pump housing
Measure supply voltage at pump connector during command (low-voltage and/or HV as applicable)
Measure pump motor current draw while commanded on (compare to expected)

Signal parameters

Command signal: PWM duty 0–100% or ON/OFF; check whether control module is commanding Pump B
Supply voltage: typical 12 V or vehicle-specific low-voltage supply when commanded ON; some systems use HV supply — consult vehicle docs
Motor current draw: expected idle/run range dependent on pump (example: 0.5–5 A for 12 V motors; HV motors higher) — stalled condition often shows very low rpm but higher than normal current or open circuit
Feedback: some pumps provide tachometer or hall-sensor pulses; expected pulse frequency proportional to commanded speed
Resistance: static winding resistance expected low ohms (consult service data); open/infinite or short to ground indicates electrical fault

Diagnostic algorithm

Retrieve all related codes and live data from BMS/thermal control module. Note command status for Pump B and any other thermal pump commands.
With vehicle in a safe condition (ignition/ready state per service manual), command Pump B ON while monitoring live data: verify controller command, supply voltage at pump connector, and any tachometer/feedback signal.
If controller commands pump but no voltage present at pump connector, inspect fuses, relays, HV interlock, and wiring back to driver module. Repair continuity/open circuits as needed.
If voltage present but pump does not run and current is near zero, disconnect pump and bench-test pump with appropriate safe supply per vehicle spec (observe HV safety procedures). If pump fails to run, replace pump assembly.
If pump runs on bench but stalls when installed, inspect mechanical load: check impeller free-play, debris in cooling circuit, collapsed/blocked hoses, or airlock. Flush/clean cooling circuit and replace damaged components.
If pump draws excessive current when commanded (possible stall) measure voltage drop, inspect driver module and high-current wiring, and check for high resistance connections. Test or replace driver/inverter if necessary.
If pump driver module is suspected, follow manufacturer procedures to test driver electronics. Reflash/update control module software if TSBs indicate a software remedy.
After repair, clear codes and perform functional test: verify pump operation under multiple conditions, monitor temperatures and re-scan for codes. Confirm proper system cooling and that DTC does not return.

Likely causes

Pump motor mechanically jammed (impeller contact with debris or broken shaft)
Power feed to pump is absent due to blown fuse, relay, or disconnected connector
Pump driver electronics failed and not providing PWM/current
High-resistance connection causing insufficient current and apparent stall
Coolant flow restriction (frozen, blocked hoses, or radiator blockage) preventing rotation under load