Home / DTC / P26CA — Engine Coolant Pump Control Circuit/Open

P26CA — Engine Coolant Pump Control Circuit/Open

Detailed page for trouble code P26CA.

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Code

P26CA

Generic P — Powertrain

Engine Coolant Pump Control Circuit/Open

Brand: Generic
Views: UK: 16 EN: 19 RU: 44
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Page language: EN

Causes

  • Open or broken wiring between ECM/PCM and coolant pump
  • Blown fuse or faulty relay in pump power feed
  • Corroded, loose or damaged connector/terminal at pump or module
  • Failed coolant pump motor (open winding)
  • Poor ground connection for pump or module
  • Faulty ECM/PCM driver output or internal module fault

Symptoms

  • Cooling system not circulating when expected (reduced heater flow, higher engine temperature)
  • MIL (check engine light) illuminated
  • Diagnostic trouble code P26CA stored
  • Possible unusual noises if pump partially functioning
  • No voltage or control signal present at pump connector when commanded

What to check

  • Retrieve freeze frame and live data with scan tool; confirm P26CA and any related codes
  • Visual inspection of pump, wiring harness, connectors, fuses and relays for damage/corrosion
  • Check for blown fuse(s) or tripped circuit protection on pump circuit
  • Command pump ON using a scan tool and observe behavior (pump operation, current draw, voltage)
  • Measure battery voltage at pump power pin with ignition ON and while commanded ON
  • Measure resistance of pump motor windings (with battery disconnected) and compare to spec

Signal parameters

  • Battery feed (constant or switched): ~12 V nominal (11–14.5 V while running) when fused/relay closed
  • Control output: PWM or switched ground from ECM/PCM — typical duty 0–100% when commanded, frequency may vary by model (common range 20–200 Hz)
  • Expected pump motor resistance (typical): low ohms — often 0.2–10 Ω depending on pump design (compare to OEM spec)
  • Continuity: near-zero ohms between pump negative and chassis ground when good
  • Current draw when running: varies by pump (often 1–10 A); very low or open indicates open winding, very high indicates stalled motor

Diagnostic algorithm

  1. Read and record all DTCs and freeze frame/live data. Note if multiple related codes present.
  2. Perform a visual inspection of pump, harness, connectors, fuses and relays. Repair obvious damage before further testing.
  3. Verify fuses and relays for the coolant pump power circuit. Replace if blown or faulty and retest.
  4. With connector disconnected and battery negative disconnected, measure pump motor winding resistance. If open/infinite → suspect failed pump motor.
  5. Reconnect battery. Backprobe pump connector. With ignition ON (engine off) check for battery feed on the power pin. With scan tool, command pump ON and verify control pin behavior (voltage or PWM) and that power feed is present.
  6. If power feed exists but control signal is absent, trace continuity from ECM/PCM output to pump connector; check for open or high-resistance circuit, repair wiring as needed.
  7. If control signal exists at connector but pump does not run and windings were within spec, check ground continuity and measure current draw while commanding pump. Replace pump if it draws no/very low current or excessive current.
  8. If wiring and pump test good, test or substitute the relay (if present). If relay and wiring OK but control output from ECM is incorrect, inspect ECM grounds and power. Consider module replacement only after verifying wiring and load.
  9. After repairs, clear codes and perform functional test (command pump, run vehicle to operating conditions) and re-scan to confirm code does not return.

Likely causes

  • Open/shorted wire or broken connector to coolant pump
  • Blown fuse or stuck/failed relay in pump feed circuit
  • Corroded connector at pump causing intermittent/ open contact
  • Failed pump motor windings (open)
  • Bad ground at chassis or module

Fault status

⚠️ Status
P26CA — Engine Coolant Pump Control Circuit/Open. The PCM detected an open or missing control/power circuit to the engine coolant pump. Circuit-level fault requires inspection of fuses/relays, wiring, connectors, ground, pump motor and PCM output.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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