Possible causes
– Faulty Fuel Level Gauge
– Fuel Level Gauge harness is open or shorted
– Fuel Level Gauge circuit poor electrical connection
– Faulty Powertrain Control Module (PCM)
– Fuel Level Gauge harness is open or shorted
– Fuel Level Gauge circuit poor electrical connection
– Faulty Powertrain Control Module (PCM)
When is the code detected?
If the fault detection circuit senses a voltage other than what the PCM expects, the fault line status changes causing the P0656 code will set.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0656 GMC Description
The Powertrain Control Module (PCM) controls the fuel gauge through the fuel gauge control circuit. The PCM supplies a pulse width modulated (PWM) duty cycle signal to control the fuel gauge. The PCM receives the fuel level information from the fuel level sensor.
The PCM controls the gauge by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. Each driver has a fault line which the PCM monitors.
The PCM controls the gauge by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. Each driver has a fault line which the PCM monitors.