Circuit Description
The fuel level sensor changes resistance based on the amount of fuel in the fuel tank. The fuel level sensor has a common, or shared 5-volt reference circuit and a signal circuit. The engine control module (ECM) applies 5 volts on the reference circuit to the sensor. The ECM monitors the changes in this voltage on the signal circuit, caused by a change in the resistance of the fuel level sensor, in order to determine fuel level. The fuel level sensor is part of the fuel sender, and is serviced as an assembly.
When the fuel tank is full, the sensor resistance is low, and the ECM signal voltage is high. When the fuel tank is empty, the sensor resistance is high, and the signal voltage is low.
The ECM uses inputs from the fuel level sensor in order to calculate the total fuel percentage remaining in the fuel tank. The ECM uses the fuel level information for the EVAP and misfire diagnostics. The fuel level information is sent to the instrument panel cluster (IPC).
If the ECM detects a signal voltage higher than the operating range of the sensor, this DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P0463 Fuel Level Sensor Circuit High Voltage
Conditions for Running the DTC
| • | The engine is running. |
| • | DTC P0463 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The fuel level signal voltage is more than 4.8 volts.
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. |
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, load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.
Test Description
The number below refers to the step number on the diagnostic table.
-
This step verifies that a condition exists.
-
This step tests the signal circuit for a short to voltage. If the scan tool displays a voltage after the fuel sender assembly harness connector is disconnected, the circuit is shorted to a voltage.
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This step tests the 5-volt reference circuit for a short to voltage. Other sensors that share the 5-volt reference circuit may also have DTCs set. Test the shared 5-volt reference circuits and sensors for a short to voltage, if the voltage measured is more than the specified value.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector 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 | |
Is the voltage less than the specified value? | 4.8 V | Go to Step 3 | Go to Step 4 | |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids |
Is the voltage less than the specified value? | 0.2 V | Go to Step 5 | Go to Step 6 | |
Measure the voltage between the 5-volt reference circuit of the fuel level sensor and a good ground, with a DMM. Is the voltage more than the specified value? | 5.2 V | Go to Step 7 | Go to Step 8 | |
6 | Test the signal circuit of the fuel level sensor for a short to voltage. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
7 |
Important: The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5-volt reference circuit of the fuel level sensor and all the shared 5-volt reference circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Test for shorted terminals and poor connections at the fuel sender assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the fuel sender assembly. Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the control module. Refer to Engine Control Module Replacement for the 1.6L (L91) engine or, Engine Control Module Replacement for the 2.0L (L34 GMDAT) engine. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Are there any DTCs that have not been diagnosed? | -- | System OK | |
