GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Vivant 🢒 DTC 🢒 DTC P0656

Circuit Description

The engine control module (ECM) creates the fuel gage output signal by pulsing the circuit to ground. The ECM monitors the voltage on the fuel gage output circuit. If the ECM determines that the voltage is out of the normal operating range, a DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0656 Fuel Level Output Circuit

Conditions for Running the DTC
    • The engine is running.
    • The ignition 1 voltage is more than 10 volts.
    • This DTC runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the signal circuit do not match.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The ECM will store conditions which were present when the DTC was set as Failure Records data only.
    • This information will not be stored in the Freeze Frame data.

Conditions for Clearing the MIL/DTC
    • DTCs can be cleared by using the scan tool.
    • Disconnect the ECM battery feed for more than 10 seconds.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connect End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Start the engine.
  2. Allow the engine to idle for 1 minute.

Does DTC P0656 fail this ignition?

Go to Step 4

Go to Step 3

3
  1. Turn OFF the ignition for 30 seconds.
  2. Start the engine.
  3. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

Go to Step 4

Go to Diagnostic aids in Diagnostic System Check - Vehicle

4

Are DTCs P0654 and P1661 also set?

Go to Step 7

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Install one lead of the Signal Generator and Instrument Panel Tester to the fuel gage signal circuit at the ECM harness connector, and the other lead to a good ground.
  4. Turn ON the ignition, with the engine OFF.
  5. Set the Signal Generator and Instrument Panel Tester to generate a speedometer signal.

Does the fuel gage change?

Go to Step 9

Go to Step 6

6

Test the fuel gage signal circuit for the following conditions:

    • An open
    • A short to ground
    • A short to voltage
    • High resistance

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 10

7

Test the ignition 1 voltage circuit of the instrument panel cluster (IPC) for the following conditions:

    • An open
    • A short to ground
    • An open fuse
    • A short to voltage
    • High resistance

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 8

8

Test the ground circuit of the instrument panel cluster (IPC) for an open circuit or for high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 10

9

Inspect for poor connections at harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the ECM.

Did you complete the replacement?

Go to Step 13

--

12

Replace the IPC.

Did you complete the replacement?

Go to Step 13

--

13
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 14

14

Are there any DTCs that have not been diagnosed?

Go to Diagnostic System Check - Vehicle

System OK