OBD-II Trouble Code Description for P0620 GMC

Generator Control Circuit

What does this mean?

OBD2 Code P0620 GM definition:
The PCM uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is desired, the PCM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit.

Symptoms

Possible sumptoms of OBD code P0620 GM
– Engine Light ON (or Service Engine Soon Warning Light)

Causes

Possible causes of OBD code P0620 GM
– Failed Generator/Belt – Battery charge – PCM controlled generator – PCM failure – Open or short generator circuit The Error code is generally activated on detection of the following conditions: The PCM has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.

Possible Solutions