P0656

Circuit Description

The 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. If the fault detection circuit senses a voltage other than what the PCM expects, the fault line status changes causing the DTC to set.

Conditions for Running the DTC

- The engine speed is greater than 600 RPM.
- The ignition voltage is between 6.0 volts and 16.0 volts.

Conditions for Setting the DTC

- The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
- All the above conditions present for a minimum of 10 seconds.

Action Taken When the DTC Sets

- The PCM stores the DTC information into memory when the diagnostic runs and fails.
- The Malfunction Indicator Lamp (MIL) will not illuminate.
- The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the MIL/DTC

- A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
- Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

- An open GAGE fuse causes DTC P0656 to set. The instrument cluster is inoperative with an open GAGE fuse.
- The C210 connector half with the female terminals is the gauge side of the circuit. The connector half with the male terminals is the PCM side of the harness.
- The following may cause an intermittent:
- Poor connections: Check for adequate terminal tension.
- Corrosion
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
- Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. Fuel level DTCs set causes the fuel gauge to display empty. Do not perform this DTC table if DTCs P0461, P0462, or P0463 are set. Only perform this table if a DTC P0656 is set.
5. The C210 connector is located behind the right side (passenger side) kick panel. Connector C210 contain circuits for the fuel tank pressure sensor and the fuel level sensor. Disconnecting this connector causes additional DTCs to set. If the gauge displays empty, this indicates the circuit between the C210 connector and the gauge is shorted to ground or the gauge is malfunctioning.
7. This step determines if the circuit between the gauge and the C210 connector is open. If the gauge goes to empty, this indicates the circuit and the gauge are OK.
8. This step determines if the PCM is capable of controlling the gauge. If the test lamp changes brightness, the PCM and circuit are OK.