P2600

Symptoms

• Check engine light (possibly flashing) with the temperature gauge climbing rapidly after start-up
• coolant temperature warning lamp illuminated
• "Engine cooling system" or "Coolant pump failure" message on the cluster or infotainment display
• engine overheating
• possible loss of cabin heat.

Probable causes

• Faulty coolant pump control relay (most common per sources)
• open or corroded wiring
• connectors or blown fuse in the pump control circuit
• broken ground wire or loose control module ground strap
• coolant pump motor internal failure with excessive current draw
• internal failure of the ECM driver transistor or a software fault disabling the output.

Diagnostic steps

1. Scan for P2600, verify whether it is the only active code, record freeze-frame data, then clear and retest to confirm the fault is current.
2. Visually inspect the pump harness and connectors for cracked insulation, loose pins, corrosion, or coolant residue; clean terminals and repair wiring as needed.
3. Check the pump fuse and relay: measure resistance across the fuse and swap the relay with a known-good unit.
4. With ignition ON, measure voltage at the pump power lead (expect battery voltage, ~12 V, per source).
5. Command the pump to run with a scan tool (active test) and observe voltage at the pump while it is commanded on; check the ground circuit with a test light during actuation.
6. Test the pump motor resistance to detect internal failure.
7. Disconnect the pump connector and measure the ECM output pin voltage during the command; if there is no output with good wiring, suspect the ECM.
8. Repair or replace the faulty component (wiring, fuse, relay, pump motor, or ECM), clear the code and verify coolant temperature stays normal.