P008D: Fuel Cooler Pump Control Circuit Low

What it means

Control voltage of the fuel cooler pump is below the expected range — short to ground or low-resistance fault.

At a glance

• Usually lights the check-engine light

How it works

The fuel cooler pump circulates fuel through a cooler in systems equipped with one, and the control module monitors its electrical control circuit. P008D sets when circuit voltage is lower than expected, often because the control wire is shorted to ground or a poor connection pulls the signal down.

Common causes

Most likely first.

1. Wiring shorted to ground
2. Connector pins corroded - high contact resistance
3. Harness chafing through insulation

Symptoms

• Check engine light on
• Fuel system warning light, if equipped
• Reduced engine performance in hot conditions

How to diagnose it

1. Save freeze-frame data and check for fuel-system warnings or related pump circuit codes.
2. Inspect the fuel cooler pump harness for chafing, crushed sections, exposed wire, or moisture and corrosion at the connector.
3. Check connector pins for looseness or corrosion that could create high contact resistance.
4. With the circuit isolated as directed by the wiring diagram, test for a short to ground and check continuity through the control wire.
5. Verify pump circuit operation and control voltage against the manufacturer's specification, then check the module output if the wiring and pump pass.

Common fixes

• Clean and secure corroded or loose fuel cooler pump connector terminals.
• Repair chafed wiring or a control wire shorted to ground.
• Replace damaged connector seals or terminals that allow moisture ingress.
• Replace the pump or control component only if testing confirms it is causing the low circuit reading.

Can I keep driving?

If the engine runs normally, limit driving in hot weather and avoid sustained heavy loads because the fuel cooler pump may not operate correctly. Stop if fuel-system warnings appear with loss of power or rough running.