P1646 CHEVROLET – EVAP Vent Solenoid Output Circuit

P1646 CHEVROLET Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P1646 CHEVROLET Possible Causes

Faulty EVAP Vent Solenoid,EVAP Vent Solenoid harness is open or shorted,EVAP Vent Solenoid circuit poor electrical connection

P1646 CHEVROLET Description

The Powertrain Control Module (PCM) contains chips called Output Driver Modules that provide 7 switchable ground outputs for operating solenoids, relays, telltales, and other devices. Each of these ground outputs has an internal fault line that feeds back to the PCMs microprocessor. When the output is OFF, the output driver should receive the 12 volts fed to the solenoid, relay, etc. When the output is ON, it should receive 0 volt since it is grounding the output. If it receives 0 volt when the output is OFF or 12 volts when the output is ON, it sets the fault line low.