The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a Voltage regulating circuit located within the Powertrain Control Module (PCM) . The EVR is not serviced separately. If replacement is necessary, the PCM must be replaced.
Operation: The amount of DC current produced by the generator is controlled by EVR circuitry contained within the PCM. This circuitry is connected in series with the generators second rotor field terminal and its ground.
Voltage is regulated by cycling the ground path to control the strength of the rotor magnetic field. The EVR circuitry monitors system line Voltage and battery temperature . It then compensates and regulates generator current output accordingly.
Failed battery temperature sensor could disable the charging
Here is how to test:
#1 Disconnect the sensor from the engine harness.
#2 Attach ohmmeter leads to the wire terminals of the sensor.
#3 At room temperature of 25 °C (75 - 80 °F) , an ohmmeter reading of 9k to 11k ohms should be observed.
#4 If reading is above or below the specification, replace the sensor.