For 1990-2009 cars

### Circuit Description

The fuel tank sending unit consists of a float that rides on the surface of the fuel in the tank and a variable resistor controlled by the float arm. When voltage is supplied to the fuel gage, current flows through the gage to the variable resistor and then to ground. The position of the display is determined by the amount of current flowing through the gage. The fuel level sender signal circuit connects to the instrument panel cluster (IPC) and a splice in this circuit provides a signal to the engine control module (ECM).

As the fuel level decreases the sending unit resistance increases, and when the fuel level increases, the sending unit resistance decreases. The display of the correct fuel level is dampened slightly upon start-up, cycling of ignition, and will stabilize after approximately 12 seconds.

### Conditions for Setting the DTC

• | The fuel level sensor voltage at the ECM is more than 4.8 volts or less than 0.1 volts.

• | The above condition is present for 1 second.

### Action Taken When the DTC Sets

The ECM will not illuminate the malfunction indicator lamp (MIL).

### Conditions for Clearing the MIL/DTC

• | A history diagnostic trouble code (DTC) clears after forty consecutive warm-up cycles in which there are no failures reported by this diagnostic or any other non-emission related diagnostic.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

### Test Description

The number below refers to the step number on the diagnostic table.

1. This test determines whether the open is in the fuel level signal circuit or if there is an internal engine control module problem.

2. Clear all DTCs within the ECM after performing this diagnostic table.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Instrument Cluster Schematics
1 | Did you perform the IPC Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Instrument Cluster
2 | Is DTC 167 or DTC 168 present in the IPC? | Go to Diagnostic Trouble Code (DTC) List | Go to Step 3
3 |

1. Disconnect the engine control module connector C2.
2. Test the fuel level signal circuit for an open at the ECM connector C2. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4 | Important: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls. Did you complete the replacement? | Go to Step 5 | --
5 |

1. Use the scan tool in order to clear the ECM DTCs.
2. Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2