P2603 Fault Code

Coolant Pump Control Circuit High

• What does that mean?
• Symptoms
• Causes
• Solutions

The P2603 fault code indicates that there is an issue with the coolant pump control circuit, specifically that the circuit is experiencing a high voltage condition. This can lead to insufficient cooling for the engine or hybrid battery, which can affect performance and longevity. The cooling system is crucial for maintaining optimal operating temperatures.

What are the symptoms of the P2603 code?

Common symptoms associated with P2603 may include:

• Overheating engine or hybrid battery due to inadequate cooling.
• Reduced performance or efficiency in hybrid vehicles.
• Warning lights or check engine light illuminated on the dashboard.
• Unusual noises from the coolant pump or related components.
• Possible engine shutdown to prevent damage from overheating.

What causes the P2603 code?

This fault can be caused by several factors, including:

• A short circuit in the coolant pump control circuit.
• An open circuit that affects the power supply to the coolant pump.
• A malfunctioning coolant pump that draws too much current.
• Faulty wiring or connectors within the circuit that may cause resistance or voltage drops.
• ECM (Engine Control Module) programming issues that could misinterpret the pump’s operational status.

How to fix P2603?

To resolve the P2603 fault code, the following steps should be taken:

• Inspect the coolant pump and its wiring for any visible damage, shorts, or corroded connections.
• Use a multimeter to check the voltage supply to the coolant pump; ensure it aligns with manufacturer specifications.
• Test the coolant pump operation by applying direct battery voltage to see if it functions as expected.
• Replace the coolant pump if it is found to be defective.
• Clear the diagnostic trouble codes from the system and perform a test drive to monitor the performance and ensure the code does not return.