P008D Low rate of the fuel cooler pump control circuit

P008D Low rate of the fuel cooler pump control circuit

OBD-II DTC Datasheet

Low signal level in the fuel cooler pump control circuit

What does this mean?

This Generic Transmission Diagnostic Trouble Code (DTC) is usually applied to vehicles with OBD-II diesel engines. This may include, but is not limited to, Ford / Powerstroke, BMW, Dodge / Ram / Cummins, Chevrolet, GMC, etc. Despite the general nature, specific repair steps may vary depending on the make / model.

DTC P008D is one of several possible codes associated with diesel vehicles that indicates that the powertrain control module (PCM) has detected a malfunction and operation of the fuel cooler pump control circuit that is built in to facilitate proper diesel operation. engine.

Codes that are commonly associated with fuel cooler pump control circuit malfunctions are P008C, P008D, and P008E.

The fuel cooler pump control circuit is designed to control the operation of the fuel cooler pump. This feature is typical for diesel vehicles and is designed to cool the excess fuel before returning the fuel to the fuel supply system. The fuel is cooled by a fuel cooler that works in a similar way to a radiator using coolant to remove heat from the fuel.

The temperature of the pump is controlled by the fuel cooler pump control circuit, which activates the pump to direct fuel through the fuel cooler assembly before returning the fuel to the fuel tank. This process will depend on the specific diesel vehicle and fuel system configuration. The end result is the same, ensuring optimal performance and protection of fuel system components.

Depending on the specific diesel vehicle involved, the PCM may activate various other codes as well as turn on the check engine light.

P008D is set by the PCM when the fuel cooler pump control circuit is low.

In this photo you can see the fuel cooler, lines and the fuel cooler pump (center) connected to the lines:

What is the severity of this DTC?

The severity level of this code starts at moderate depending on the specific problem and the severity level will progress. Hot fuel temperatures are undesirable and can cause excessive wear on fuel system components as well as excessive wear on internal engine components if not corrected in a timely manner.

What are some of the symptoms of the code?

Symptoms of a P008D engine code may include:

• Reduced engine power
• Acceleration and surging at idle speed
• Check Engine light is on
• Increased fuel consumption
• Fuel cooler pump noise

What are some of the possible reasons for the code to appear?

Reasons for this code may include:

• Fuel cooler pump defective
• Corroded or damaged connector
• Faulty or damaged wiring
• Defective PCM

What are some steps to troubleshoot the P008D?

Locate all components related to the fuel cooler pump control circuit. This will include the fuel cooler pump, fuel cooler, fuel cooler reservoir and PCM in a simplex system. Once these components are found, a thorough visual inspection should be performed to check all associated wiring and connectors for obvious defects such as scratches, scuffs, bare wires, or burn spots. Coolant leakage signs, fluid level and condition should also be included in this process.

Advanced steps

The additional steps become very vehicle specific and require appropriate advanced equipment to be performed accurately. These procedures require a digital multimeter and vehicle-specific technical reference documents. Voltage requirements depend on the year of manufacture, model and diesel engine of the vehicle.

It is also helpful to check the Technical Service Bulletins (TSBs) for your specific vehicle, as this could be a known issue and fix that could save you money and time while diagnosing.

Checking circuits

Voltage requirements will vary depending on the specific engine, the fuel cooler pump control circuit configuration, and the components included. Refer to the technical data for the correct voltage range for each component and the appropriate troubleshooting sequence. A correct voltage across an inoperative fuel cooler pump usually indicates an internal malfunction. A malfunctioning fuel cooler pump can also emit a squeal that will develop to the point where it can emit a dog-like barking.

If this process detects that a power source or ground is missing, a continuity check may be required to check the condition of the wiring and connectors. Continuity tests are always performed with power removed from the circuit and normal readings should be 0 ohms of resistance unless otherwise specified in the specifications. Resistance or no continuity indicates faulty wiring or connectors that are shorted or open and should be repaired or replaced.

What is a routine repair?

• Replacing the fuel cooler pump
• Cleaning connectors from corrosion
• Repair or replacement of wiring
• Flashing or replacing PCM

Hopefully the information in this article has helped point you in the right direction for solving the problem with your fuel cooler pump control circuit. This article is for informational purposes only and specific technical data and service bulletins for your vehicle should always take priority.

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