The driver requires a calibration resistor. This resistor matches the injector pump, not the driver. It is intended to help the engine computer compensate for the minor manufacturing differences in injection pumps. When you replace a driver, you can re-use the old resistor or obtain a same- or similar-numbered replacement resistor.
The resistor value is remembered by the engine computer. It is only re-read when the computer forgets the value. This may happen immediately, or not for several months.
The resistor is located inside the electrical connection on the driver.
Resistor number and location:
Resistors can be removed with small snap ring pliers by using the two small holes in the resistor circuit card.
Currently, only 2 resistors are available: #5 and #9.
The #5 resistor is the most common, and is guaranteed to work with any pump.
The #9 will add a very small amount of additional fuel. This will add a very small amount to the performance, and will add a very small amount to the emissions.