Coolant Pump Control Circuit Low
The P2602 code indicates that the Engine Control Module (ECM) has detected a low voltage condition in the control circuit of the coolant pump. This pump is responsible for circulating coolant through the engine and heater core. A low circuit voltage typically points to a wiring issue, a faulty pump, or a problem with the ECM itself. If left unresolved, it can lead to engine overheating and potential damage.
1. Most Common Causes
- Faulty electric coolant pump (internal winding shorted to ground or open circuit)
- Short to ground in the pump control circuit wiring
- Corroded, loose, or damaged connector or terminal at the pump harness
- Excessive resistance in the control circuit due to poor splices or deteriorated wiring
- Internal failure of the ECM/PCM power driver
- Blown or defective coolant pump fuse or relay (if applicable to circuit design)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine overheating
- Poor heater performance
- Coolant leaks
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the coolant pump wiring and connector for damage or corrosion.
Step 3: Test the coolant pump control circuit voltage with a multimeter.
Step 4: Check the coolant pump resistance and compare to specifications.
Step 5: If wiring and pump are okay, test the ECM output signal.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The coolant pump may not be working, leading to engine overheating and potential severe damage. Have the vehicle inspected immediately.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, but can be higher if the pump or ECM needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.