P2C48

Code

Generic P — Powertrain

Coolant Pump C Control Circuit Performance/Stuck Off

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 122 RU: 24

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Page language: EN

Causes

Open or shorted wiring in the coolant pump C control circuit
Corroded, loose, or damaged connector at the pump or ECM
Failed coolant pump (seized rotor or open motor)
Failed pump control relay or fuse
ECM/PCM driver fault or software anomaly
Low coolant level or blocked passage preventing pump operation

Symptoms

Malfunction Indicator Lamp (MIL) or check engine light illuminated
Engine overheating or elevated coolant temperature under load
Reduced HVAC heater flow (cold or no heat) if pump affects heater circuit
Reduced cooling system performance, long warm-up or hot spots
Possible fault-dependent limp mode or reduced engine power
No audible pump operation when pump should run

What to check

Retrieve DTC, freeze frame and related codes with a scan tool
Confirm coolant level and visually inspect cooling system for blockages or leaks
Inspect fuses and relays for the coolant pump circuit
Visual inspection of wiring harness, connector terminals and grounds for damage or corrosion
Backprobe control and power pins at the pump while commanding pump ON with a scan tool
Measure pump motor resistance and compare to specification

Signal parameters

Control type: PWM switching from ECM (typically 0–12 V switching; duty cycle 0–100%)
Expected control voltage: ~0 V when off, full battery voltage when commanded on depending on design
Typical PWM frequency range (vehicle dependent): tens to a few hundred Hz
Motor resistance: low-ohm value (vehicle-specific); open circuit indicates failed motor
Current draw while running: typical pump motors draw from ~1 A up to 10 A depending on design — check spec
Engine coolant temperature and commanded duty cycle should correlate (higher temp = higher duty)

Diagnostic algorithm

Record DTC, freeze-frame data and any related codes. Note when and under what conditions the code set (temperature, vehicle speed, engine load).
Visually inspect coolant level, pump area, wiring harness and connectors for obvious damage, corrosion or disconnection. Repair any obvious issues and clear codes to retest.
Check fuses and relays for the coolant pump circuit. Replace if blown or suspect. Verify relay socket power/ground.
Backprobe the pump connector with a multimeter or oscilloscope while commanding pump ON with a scan tool. Verify presence of battery power to the pump and that the ECM provides the expected control signal (voltage or PWM duty).
If no control signal from ECM but battery power present, check continuity between ECM and pump control pin, inspect for opens/shorts, and check grounds. Repair wiring as needed.
Measure motor winding resistance at the pump. An open or very high resistance indicates internal motor failure — replace pump. If resistance is normal, bench-power the pump (with appropriate fuse and safety precautions) to confirm it runs and to measure current draw.
If pump runs when bench powered but not when vehicle commanded and wiring is good, suspect ECM driver fault. Confirm with manufacturer diagnostics before replacing ECM.
After repairs, clear codes and perform warm-up and drive cycle to verify pump operation, proper temperature regulation and that code does not return.
If intermittent, perform wiggle tests on harness/connector while monitoring live data and control signal to reproduce the fault.

Likely causes

Failed coolant pump C (electrical motor failure or mechanical seizure)
Open or high-resistance wiring or connector between ECM and pump
Blown fuse or faulty relay in pump power feed
Bad ground at pump or engine ground strap
ECM output transistor or driver failure

Fault status

⚠️ Status

P2C48 — Coolant Pump C Control Circuit Performance/Stuck Off. ECM reports that Coolant Pump C did not respond to commanded control (stuck off) or control circuit performance is out of expected range. Check pump, power/ground, wiring and ECM driver.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours