P0627 toyota


  • P0627 – Fuel pump control -circuit open
  • Common problems associated with the Denso HP2 fuel system
  • P0627 Citroen Fuel Pump Control System Malfunction
  • Error Code P0627: Fuel Pump “A” Control Circuit /Open
  • P0627 Fuel Pump Control Circuit A / Open
  • Toyota P0627 Fuel Pump Control System Malfunction
  • P0627 – Fuel pump control -circuit open

    Looking on the back of the pump you will see there are two electrically operated solenoids — one red and one green see image right. Why two? Well the system is not like any other. The job of the SCV is to control the flow of fuel oil to the pumping chamber of the high pressure pump, as a means of controlling the pressure in the common rail.

    The pumping chamber in other systems including Bosch, Siemens and Denso HP3 , consists of a cam, piston and powerful spring. The spring provides the inlet stroke and the cam provides the outlet stroke; this means that the engine has to provide a large amount of power to operate the pump. The Denso HP2 system uses a single internal eccentric cam and two pumping chambers.

    In the image below Chamber 2 is on the intake stroke; fuel from the internal feed pump enters the chamber via the check valve when the SCV is open and forces the pistons apart. The amount of fuel entering the chamber is controlled by how long the SCV is open during the intake stroke. A short opening time will only partially fill the chamber, by moving the pistons out a reduced amount so that the rollers do not touch the cam.

    This means the cam has to turn until the rollers touch the cam and start the outlet stroke. This diagram shows a schematic of the system The amount of fuel delivered to the common rail is a function of the angle through which the rollers are in contact with the cam shaded red below. Both the contact angle and the common rail pressure are parameters on your scan tool; the relationship between engine speed, contact angle, injection quantity and common rail pressure are monitored for plausibility.

    The single pumping chamber Pump timing Unlike the SCVs in other systems where the opening of the valve is controlled in degrees by using Pulse Width Modulation , the Denso HP2 system uses a timed open period.

    The result of this is less effort required to operate the pump. As a result of this method of control, the opening of the SCV has to be timed to allow the flow of fuel into the chamber when the internal cam is at its maximum stroke. This means that the pump drive pulley has to be timed to the engine.

    This must be kept in mind when replacing the cam belt. What goes wrong? The SCV fails to respond to the control signal correctly; this can be caused by various reasons but, essentially, they stick.

    There has been some speculation about the reduction of the lubricating properties in modern diesel fuel due to the reduction of sulphur. Sulphur is not a lubricant but it can combine with the nickel content in many metal alloys to form an alloy that can increase lubrication.

    Over the years of production small modifications have been made to the design of the SCVs to overcome the problem, but there are still plenty of older vehicles out there that have the potential to fail. Symptoms of SCV failure The most common symptoms are a lack of power or rough idling; both these faults may be intermittent. DTCs P and P relate to excessive pressure in the system caused by the SCV sticking open longer than it should and will cause the engine to go into failsafe mode where the engine power is restricted.

    The wiring from the engine ECU to the valves should also be checked for continuity; for this you will need a wiring diagram. A quicker test can be carried out using a good oscilloscope, such as the one on the G-Scan 2. The image below shows a capture from the G-Scan 2. The scope is set up to show three of the four possible channels; channels A1 and B1 are connected to the PCV 1 and 2 terminals and a common ground.

    The rapid switching effect is used to limit the current through the SCV winding and prevent overheating. The clean scope pattern shows that the wiring is intact. It should be noted that cleanliness is of paramount importance; the ingress of the smallest particle could cause the valves to malfunction. Clean around the area with brake cleaner and use an air gun to remove any small particles.

    You may wish to disconnect the upper hose and plug to give you more room. Make sure that the area around the green and red SCVs is as clean as possible to reduce the risk of debris entering the pump.

    Common problems associated with the Denso HP2 fuel system

    Engine turns normally but will not start Engine stalls when operating temperature is reached Note. The issue may not really be resolved even if the check engine light does not come on immediately. Always make sure your vehicle goes through multiple driving cycles. What are some of the common causes for the code?

    Reasons for this code may include: Problems with the fuel pump itself Broken or damaged ground wire in the control module of the device. The first thing I recommend that you do is review the vehicle-specific Technical Service Bulletins TSBs by year, model, and powertrain. In some cases, this can save you a lot of time in the long run by pointing you in the right direction. You should also always do a visual inspection of the connectors and wiring if there is anything clearly damaged in which case it should be repaired or replaced.

    They are often located under the vehicle next to the fuel tank. They are susceptible to road debris and elements, so pay close attention to their health. Basic step 2 When working on any component with its own module such as a fuel pump module, etc.

    This can be done by using a separate battery ground. This is sometimes easy to do with an auxiliary ground cable. If your problem is resolved with an auxiliary ground connected, but then returns when an OEM ground is used, this would indicate that your ground cable is causing the problem and needs to be repaired or replaced. Always carefully check the ground connection for corrosion. A good sign of excessive corrosion is a green ring around the connector attached to the positive battery post.

    Basic step 3 Given that an open circuit could be the cause of the P code, you should identify the circuit using the circuit diagram in your service manual.

    Once identified, you can trace the individual fuel pump control wire A separately to see if there are any obvious breaks in the wire. Repair as needed by soldering the wire which I recommend or using heat shrink butt connectors to isolate it from the elements. It is highly recommended to use a power probe tool here if there is a fault somewhere within the entire circuit.

    PC Low fuel pressure sensor B circuit I hope this article has helped point you in the right direction for diagnosing a fuel pump control circuit DTC problem. This article is for informational purposes only and specific technical data and service bulletins for your vehicle should always take priority. The truck died on the side of the road. Blown fuel pump relay fuse.

    Replaced the fuse when I got home and got the code P, the "A" fuel pump circuit is open. Any ideas? Has anyone had this problem? Need more help with the P code? If you still need help with DTC P, post a question in the comments below this article. This information is provided for informational purposes only.

    It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.

    This can be done by using a separate battery ground. This is sometimes easy to do with an auxiliary ground cable. If your problem is resolved with an auxiliary ground connected, but then returns when an OEM ground is used, this would indicate that your ground cable is causing the problem and needs to be repaired or replaced.

    Always carefully check the ground connection for corrosion. A good sign of excessive corrosion is a green ring around the connector attached to the positive battery post. Basic step 3 Given that an open circuit could be the cause of the P code, you should identify the circuit using the circuit diagram in your service manual.

    P0627 Citroen Fuel Pump Control System Malfunction

    Once identified, you can trace the individual fuel pump control wire A separately to see if there are any obvious breaks in the wire. Repair as needed by soldering the wire which I recommend or using heat shrink butt connectors to isolate it from the elements.

    It is highly recommended to use a power probe tool here if there is a fault somewhere within the entire circuit. PC Low fuel pressure sensor B circuit I hope this article has helped point you in the right direction for diagnosing a fuel pump control circuit DTC problem.

    This article is for informational purposes only and specific technical data and service bulletins for your vehicle should always take priority. The truck died on the side of the road. Blown fuel pump relay fuse. Replaced the fuse when I got home and got the code P, the "A" fuel pump circuit is open. Any ideas?

    Error Code P0627: Fuel Pump “A” Control Circuit /Open

    Has anyone had this problem? Well the system is not like any other. The job of the SCV is to control the flow of fuel oil to the pumping chamber of the high pressure pump, as a means of controlling the pressure in the common rail. The pumping chamber in other systems including Bosch, Siemens and Denso HP3consists of a cam, piston and powerful spring. The spring provides the inlet stroke and the cam provides the outlet stroke; this means that the engine has to provide a large amount of power to operate the pump.

    The Denso HP2 system uses a single internal eccentric cam and two pumping chambers. In the image below Chamber 2 is on the intake stroke; fuel from the internal feed pump enters the chamber via the check valve when the SCV is open and forces the pistons apart. The amount of fuel entering the chamber is controlled by how long the SCV is open during the intake stroke.

    A short opening time will only partially fill the chamber, by moving the pistons out a reduced amount so that the rollers do not touch the cam.

    This means the cam has to turn until the rollers touch the cam and start the outlet stroke.

    P0627 Fuel Pump Control Circuit A / Open

    This diagram shows a schematic of the system The amount of fuel delivered to the common rail is a function of the angle through which the rollers are in contact with the cam shaded red below. Both the contact angle and the common rail pressure are parameters on your scan tool; the relationship between engine speed, contact angle, injection quantity and common rail pressure are monitored for plausibility.

    The single pumping chamber Pump timing Unlike the SCVs in other systems where the opening of the valve is controlled in degrees by using Pulse Width Modulationthe Denso HP2 system uses a timed open period.

    The result of this is less effort required to operate the pump.

    Toyota P0627 Fuel Pump Control System Malfunction

    As a result of this method of control, the opening of the SCV has to be timed to allow the flow of fuel into the chamber when the internal cam is at its maximum stroke. This means that the pump drive pulley has to be timed to the engine. This must be kept in mind when replacing the cam belt. What goes wrong?


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