Circuit Description
The fuel level sensor changes resistance based on fuel level. The fuel level sensor has a signal circuit and a ground circuit. The engine control module (ECM) applies 5 volts on the signal circuit to the sensor. The ECM monitors the changes in this voltage caused by changes in the resistance of the sensor in order to determine fuel level.
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 lower than the operating range of the sensor, this DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P0462 Fuel Level Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | The engine is operating. |
| • | DTC P0462 runs continuously once the above condition is met. |
Conditions for Setting the DTC
The ECM detects that fuel level signal voltage is less than 0.2 volt.
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, engine 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 for a condition in the 5-volt reference circuit of the fuel level sensor. If the DMM does not display more than the specified voltage, test for a short to ground or an open in the 5-volt reference circuit.
-
This step tests for a condition in the signal circuit of the fuel level sensor. If the Fuel Level Voltage parameter does not display more than the specified voltage, test for a short to ground or an open in the signal circuit.
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? | 0.2 V | Go to Step 4 | Go to Step 3 | |||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||
Is the voltage more than the specified value? | 4.8 V | Go to Step 5 | Go to Step 7 | |||||||||
Is the voltage less than the specified value? | 4.8 V | Go to Step 6 | Go to Step 8 | |||||||||
6 | Test the signal circuit of the fuel level sensor for one of the following conditions:
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||
7 | Test the 5-volt reference circuit of the fuel level sensor and all shared 5-volt reference circuits for one of the following conditions:
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||
8 | Test for an intermittent and for a poor connection 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 an intermittent and for a poor connection at the engine control module (ECM). 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 11 | ||||||||
10 | Replace the fuel level sender assembly. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||
11 | Replace the ECM. 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 | |||||||||
