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.
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 evaporative emission (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 conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects that fuel level signal voltage is less than 0.2 volt. |
| • | The above condition is present for more than 10 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
| • | The fuel gage defaults to empty. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
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. |
| • | An intermittent condition |
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: Instrument Cluster Schematics Connector End View Reference: Component 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 sender assembly. Refer to Fuel Sender Assembly Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||
11 | Replace the ECM. Refer to Control Module References for ECM replacement, setup and programming. 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 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
