Technical Description of OBD-II Trouble Code
Malfunction in the Fuel Pump Primary (Control) Circuit
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to vehicles equipped with OBD-II. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The fuel pump is activated by a relay controlled by the PCM (Powertrain Control Module). The purpose of a relay is to allow the transmission of higher amperage current to the fuel pump without that current having to pass through the PCM.
It is preferable to keep higher amperage current away from the PCM to avoid potential damage. Higher amperage current generates more heat and can lead to PCM failure in the event of a malfunction. This principle applies to any relay. The higher amperages are kept separate from sensitive areas under the hood.
The relay consists of two sides: the “control” side, which is a coil, and the “switch” side, which consists of electrical contacts. The control side, or coil side, operates with low amperage. It is supplied with a switched ignition feed (12 volts with the key on) and a ground. The ground circuit is activated by the PCM driver when necessary. When the PCM fuel pump driver activates the relay coil, the coil acts as an electromagnet that closes the electrical contacts, completing the fuel pump circuit. This closed switch allows voltage to flow on the fuel pump activation circuit, activating the pump. Whenever the key is turned on, the PCM grounds the fuel pump circuit for a few seconds, activating the fuel pump and pressurizing the system. The fuel pump will not be activated again until the PCM detects an RPM signal.
The driver in the PCM is monitored for faults. When activated, the driver or ground circuit voltage should be low. When deactivated, the driver/ground potential voltage should be high or close to battery voltage. If the PCM detects a voltage other than what is expected, it may set the P0230 code.
Indications
Indications of a P0230 DTC may include:
Causes
Possible causes of a P0230 code include:
Possible Solutions
Command the fuel pump to turn on and off using a scan tool or simply by turning the ignition key on and off without starting the engine. If the fuel pump activates and deactivates, start the vehicle and measure the current on the control (ground) circuit for a couple of minutes. It should be less than one amp and remain less than one amp.
If it does not, it is advisable to replace the relay at this point. If the fuel pump does not activate and deactivate, remove the relay and visually inspect for discoloration due to heat or loose terminals. If everything appears to be in order, install a test light between the control circuit ignition feed and ground driver terminals (if unsure, do not attempt).
The test light should illuminate when the key is on or when the fuel pump is commanded on. If it does not, ensure that there is voltage on one side of the coil (switched ignition feed). If voltage is present, repair the open or short in the control ground circuit.
