P2602: Coolant Pump Control Circuit Open

What it means

The Coolant Pump A control circuit is below the expected electrical threshold. This indicates a low circuit condition, not necessarily a short to ground or failed driver.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Coolant Pump A's control circuit connects the pump with the vehicle's electrical supply or control driver. This code reports a circuit signal below the expected threshold; that low reading can result from an open pump, wiring break, or poor terminal contact and does not by itself identify a short to ground or a failed driver.

Common causes

Most likely first.

1. Pump motor open
2. Drive line open
3. Pin pushed back out of connector body

Symptoms

• Check-engine light
• Possible engine overheating or reduced cooling, if the pump is needed for engine cooling

How to diagnose it

1. Read freeze-frame data and pump command or status to see whether the low circuit reading occurred while Pump A was being requested.
2. Inspect the Pump A connector for a loose plug, corrosion, or a terminal pushed back into the connector body.
3. Trace the Pump A control wiring for breaks, chafing, or disconnected sections.
4. Measure supply, ground, and control-circuit continuity at the pump while comparing results with the manufacturer's wiring information.
5. Test the pump winding and control-module output separately to locate whether the low reading comes from the pump, wiring, or driver.

Common fixes

• Seat and secure a pushed-back or loose Pump A connector terminal.
• Repair an open or damaged Pump A control wire.
• Replace Pump A if its motor winding is confirmed open.
• Repair a confirmed control-driver fault after verifying the pump and wiring.

Can I keep driving?

If Pump A is needed for engine cooling, a low circuit reading may mean circulation is reduced, so monitor temperature closely and avoid long trips or heavy load. Stop and shut off the engine if it overheats.