P2602

Code

Generic P — Powertrain

Coolant Pump A Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 33 EN: 105 RU: 72

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Page language: EN

Causes

Blown fuse or faulty relay in coolant-pump supply/drive circuit
Open or shorted wiring (short to ground) between pump and PCM
Corroded, bent or damaged connector terminals at pump or PCM
Faulty coolant pump (motor or internal electronics)
Poor or missing ground connection
Faulty PCM/ECM output driver

Symptoms

Check Engine Light (MIL) illuminated
Coolant pump does not operate or operates intermittently
Engine running hotter than normal or overheating
Reduced heating or A/C performance (if pump affects coolant flow)
Possible limp-home mode or degraded performance depending on vehicle logic

What to check

Read and record freeze-frame and related scan data with a capable scan tool
Verify DTC is current and note any additional related codes
Attempt to command/actuate the coolant pump with a scan tool and observe response
Visually inspect wiring, connectors, fuses and relays for damage or corrosion
Measure voltage at the pump connector with ignition ON and while commanding the pump
Check continuity and resistance of wiring between pump connector and PCM

Signal parameters

Control circuit voltage OFF (open): near battery voltage (approx. 11–14 V) if the PCM uses a high-side switch; may be pulled high by supply
Control circuit voltage ON (depending on design): near 0–1 V for low-side (ground) switching, or near battery voltage for high-side switching
Expected change at PCM command vs. pump harness: voltage should change between 'off' and 'on' states when commanded by scan tool
Typical pump current when running: varies by design—often in the ampere range; excessively low or high current indicates pump or short/fault
Connector pin voltages or resistance out of specification relative to factory values indicate wiring/pump fault

Diagnostic algorithm

Verify the code: Use a scan tool to confirm P2602, record freeze-frame, and check for related codes. Do not replace parts based on the code alone.
Actuate pump via scan tool: Command the coolant pump ON/OFF while monitoring control circuit voltage and pump operation.
Visual inspection: With ignition off, inspect fuse(s), relay(s), pump connector, wiring harness along the route, and engine/PCM grounds for damage, corrosion, or loose pins.
Measure at pump: With harness connected, measure voltage at the pump control pin with ignition ON and while commanding the pump. Note whether voltage changes as expected.
Check supply and ground: Verify battery positive feed and chassis/engine ground continuity at the pump connector. Repair any poor connections.
Resistance/current test: If safe, disconnect pump and measure resistance of the pump motor (compare to spec if available) or bench-test pump with an external 12 V supply to confirm operation and current draw.
Wiring continuity: Check continuity between the pump connector and the PCM output pin; check for short to ground or short to battery. Repair damaged wiring or connectors.
Relay/fuse check: Test/replace suspect relay(s) and fuses in the pump supply/drive circuit as required.
Re-test: After repairs, clear codes, then command the pump and run vehicle to verify proper operation and that P2602 does not return.
PCM check last: If wiring, pump, fuses and relays are confirmed good and the fault persists, consider PCM output driver fault and consult manufacturer procedures for PCM testing or replacement.