Code
P26CC
Generic
P — Powertrain
Engine Coolant Pump Control Circuit Low
Views:
UK: 17
EN: 22
RU: 18
AI status
Completed
Completed
100%
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
Similar codes
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
