Coolant Pump "A" Control Circuit Low
The P2602 code indicates the PCM detected a low voltage condition in the coolant pump A control circuit. This electrical fault prevents proper control of the electric coolant pump, which can lead to inadequate coolant circulation and potential engine overheating if not addressed.
What You Might Notice
- Engine overheating or running hot
- Cooling fans running continuously at full speed
- Check engine light illuminated
- Reduced heater performance
- Potential loss of coolant flow to engine
Most Common Causes
- 1
Damaged coolant pump wiring or connector
Corroded, loose, or damaged wiring in the coolant pump control circuit can cause low voltage signals. Check connectors for corrosion, moisture, or poor contact.
- 2
Faulty coolant pump motor
The electric coolant pump itself may have failed or developed high resistance, causing the circuit to draw insufficient current and trigger a low voltage fault.
- 3
Failed coolant pump relay
A defective relay controlling the pump circuit can result in low voltage delivery to the pump motor, preventing proper operation.
- 4
PCM or control module malfunction
In rare cases, the powertrain control module itself may be faulty and unable to properly drive the pump circuit, though this is less common than wiring issues.
How to Diagnose It
- 1
Check Damaged coolant pump wiring or connector — Corroded, loose, or damaged wiring in the coolant pump control circuit can cause low voltage signals. Check connectors for corrosion, moisture, or poor contact.
- 2
Check Faulty coolant pump motor — The electric coolant pump itself may have failed or developed high resistance, causing the circuit to draw insufficient current and trigger a low voltage fault.
- 3
Check Failed coolant pump relay — A defective relay controlling the pump circuit can result in low voltage delivery to the pump motor, preventing proper operation.
- 4
Check PCM or control module malfunction — In rare cases, the powertrain control module itself may be faulty and unable to properly drive the pump circuit, though this is less common than wiring issues.
How to Fix It
- 1
Inspect and repair coolant pump wiring
Locate the coolant pump control circuit wiring and connectors. Clean any corroded connectors with electrical contact cleaner, reseat connectors firmly, and repair or replace any damaged wiring. Test voltage at the connector with the engine running.
- 2
Test and replace coolant pump relay
Locate the coolant pump relay in the engine bay fuse/relay box. Test the relay with a multimeter or swap with a known good relay of the same part number. Replace if faulty.
- 3
Replace the electric coolant pump
If wiring and relay test good, the coolant pump motor has likely failed. Drain coolant, disconnect the pump connector and mounting bolts, and install a new electric coolant pump assembly. Refill coolant and bleed the system.
- 4
Verify PCM operation and clear code
After repairs, use a diagnostic scanner to verify voltage levels in the coolant pump control circuit. Clear the trouble code and perform a test drive to confirm the issue is resolved and the code does not return.
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