What it means
Coolant pump D reports a control circuit high condition. Coolant circulation through the affected loop cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Coolant pump D circulates coolant through one of the vehicle’s cooling loops, and its control circuit carries the command used to run the pump. The module monitors that circuit and sets P2B68 when its signal is higher than expected, which can happen if the wire is shorted to battery voltage, the pump motor is open, or a connector has excessive resistance.
Common causes
Most likely first.
- Control wire shorted to B+
- Open pump motor
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Engine or a coolant-cooled component may run hotter than usual
- Cabin heat or cooling performance may be reduced
How to diagnose it
- Record freeze-frame data and check live pump D command and circuit status to see when the high condition occurs.
- With the system cool, inspect pump D’s connector and harness for corrosion, loose pins, damaged insulation, or contact with a power wire.
- Check the pump D fuse and power and ground connections against the manufacturer’s specification.
- With the pump disconnected, test the control wire for a short to battery voltage and check continuity between the module and pump.
- Measure pump D motor continuity and connector voltage under the commanded conditions, comparing results with the manufacturer’s specification.
Common fixes
- Clean and secure corroded or loose pump D connector pins.
- Repair a control wire short to battery voltage or an open in the harness.
- Repair a poor connector terminal that is causing high resistance.
- Replace pump D if its motor winding is open.
Can I keep driving?
Avoid driving if engine temperature rises, a coolant warning appears, or the vehicle enters reduced-power mode; stop safely and let it cool. Continued operation without reliable pump D circulation can overheat the engine or the component served by that loop.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.