Technical Description of OBD-II Trouble Code
The circuit controlling the fuel cooler pump is experiencing low voltage.
What does that mean?
This generic powertrain diagnostic trouble code (DTC) typically applies to diesel engine OBD-II vehicles. This includes vehicles from Ford / Powerstroke, BMW, Dodge / Ram / Cummins, Chevrolet, GMC, and others. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
Trouble code P008D is one of several codes that can indicate a malfunction in the Fuel Cooler Pump Control Circuit of diesel-powered vehicles. This circuit is responsible for facilitating the proper operation of a diesel engine.
The codes 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 specific to diesel-powered vehicles and is used to cool excess fuel before it is returned to the fuel supply system. The fuel cooler operates similarly to a radiator, using coolant to remove heat from the fuel.
The fuel cooler pump is temperature controlled by the Fuel Cooler Pump Control Circuit. It turns the pump on to route fuel through the fuel cooler assembly before returning it to the fuel tank. The specific process may vary depending on the diesel-powered vehicle and fuel system configuration. However, the end result is the same: optimal performance and protection of fuel system components.
Depending on the specific diesel-powered vehicle, the PCM may activate various other codes and illuminate the Check Engine Light.
Code P008D is set by the PCM when the Fuel Cooler Pump Control Circuit experiences a low voltage condition.
In the photo below, you can see the fuel cooler, the lines, and the fuel cooler pump (center) connected to the lines:
What is the severity of this DTC?
The severity of this code starts as moderate based on the specific malfunction, and the severity level will progress. Hot fuel temperatures are undesirable and can cause excessive wear on fuel system components and internal engine components if not addressed promptly.
What are some of the symptoms of the code?
Symptoms of a P008D engine code may include:
What are some of the possible causes of the code?
Possible causes for this code may include:
What are some P008D troubleshooting steps?
Locate all of the components associated with the Fuel Cooler Pump Control Circuit. This includes the fuel cooler pump, fuel cooler, fuel cooler reservoir, and PCM in a simplex system. Once these components are located, perform a thorough visual inspection to check all associated wiring and connectors for obvious defects such as scraping, rubbing, bare wires, or burn spots. Also, check for coolant leaks and assess the level and condition of the fluid.
Advanced Steps
The advanced steps are highly vehicle-specific and require the appropriate advanced equipment for accurate performance. These procedures necessitate a digital multimeter and the specific technical references for the vehicle. The voltage requirements will vary based on the specific year, model, and diesel engine of the vehicle.
It is also helpful to check for technical service bulletins (TSBs) for your particular vehicle, as there may be a known issue and fix that can save you time and money during diagnosis.
Circuit Checks
The voltage requirements will vary based on the specific engine, Fuel Cooler Pump Control Circuit configuration, and incorporated components. Refer to technical data to obtain the correct voltage range for each component and the appropriate troubleshooting sequence. The absence of power or ground during this process may require continuity testing to assess the condition of the wiring and connectors. Continuity tests should always be performed with the power removed from the circuit, and the normal readings should be 0 ohms of resistance unless otherwise specified by the technical data. Resistance or lack of continuity indicates faulty wiring or connectors that are shorted or open and must be repaired or replaced.
What Are Some Common Repairs?
We hope that the information in this article has been helpful in guiding you toward resolving the problem with your Fuel Cooler Pump Control Circuit. This article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.
