P26CC

Code

Generic P — Powertrain

Engine Coolant Pump Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 42 RU: 27

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Page language: EN

Causes

Open or shorted wiring in the pump control circuit (short to ground)
Poor or corroded connector at the pump or ECM
Failed or seized coolant pump motor
Blown fuse or faulty relay for pump power/control
Weak battery or poor main power/ground to pump circuit
Faulty ECM/PCM output driver or internal module fault

Symptoms

Engine temperature higher than normal or coolant temperature rising
Coolant temperature warning or MIL illumination
Reduced HVAC performance (lower heater/AC cooling) or A/C shutdown in some systems
Cooling pump not running when commanded or intermittent pump operation
Possible limp-home mode or reduced engine performance depending on strategy

What to check

Read and record stored codes and freeze frame data with a scan tool; check for related codes
Visual inspection of pump, wiring harness, connectors, and fuse/relay box for damage or corrosion
Verify battery voltage and main power/ground condition at the fuse/relay and pump
Backprobe pump control connector and measure voltage while commanding the pump on/off with scan tool
Measure pump motor resistance (ohms) and compare to specification; check for continuity to ground
Check current draw of the pump while running with a clamp meter to detect mechanical seizure or overcurrent

Signal parameters

Control signal type: typically a switched 12 V or PWM from ECM (0 V when low/inactive; up to battery voltage when driven)
Expected voltage at pump control when commanded: ~9–14 V (or PWM duty between 0–100%) depending on design
Inactive/control-low voltage: near 0 V (signal below threshold triggers 'low' fault)
Pump motor resistance (typical range): roughly 1–15 ohms (varies by vehicle; consult spec)
Typical running current: several amps to tens of amps (often 2–15 A); abnormally high or zero current indicates fault

Diagnostic algorithm

Use a scan tool to confirm P26CC and record freeze-frame data and any related codes (fans, temperature sensors, powertrain control).
Perform a visual check: inspect pump, harness, connectors, and fuse/relay for obvious damage, corrosion, or loose pins.
Verify battery voltage and ground quality at the fuse/relay box and at the pump connector (key ON, engine OFF).
Check fuse(s) and relay(s) for the coolant pump circuit; replace if faulty and retest.
Backprobe the pump control and power wires. Command the pump ON using the scan tool and observe voltage on the control and power pins. Note PWM duty if present.
If control voltage is present but pump does not run, disconnect the pump and measure its resistance. If open or out of spec, replace pump.
If no control voltage is present at connector when commanded, check continuity of control wire back to the ECM and look for short to ground. Repair wiring as required.
Measure current draw with the pump connected and commanded ON. Excessive current suggests mechanical binding; zero current with correct control voltage suggests open/failed pump.
If wiring and pump check good but ECM output remains low or intermittent, suspect ECM driver fault—verify with manufacturer diagnostics before replacing ECM.
After repairs, clear codes and recheck while performing a test run to confirm the fault does not return.

Likely causes

Failed coolant pump motor or internal pump wiring
Short to ground in control wire between ECM and pump
Blown fuse or failed pump relay
Corroded/poor connector or pin/back-shell contact
ECM output driver failure (less common)

Fault status

⚠️ Status

P26CC — Engine Coolant Pump Control Circuit Low: The control circuit for the electric coolant pump is reporting a voltage/signal below the expected threshold. Inspect power/ground, fuses/relays, wiring, connectors and the pump motor. Verify ECM command output before replacing modules.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours