Circuit Description
The powertrain control module (PCM) monitors the signal circuit of the fuel level sender in order to determine fuel level. The sender consists of a variable resistor that changes resistance based on the fuel level in the tank. The PCM monitors the voltage across the sender resistance in order to determine the fuel level. The PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel, in percent. The PCM sends the fuel level percent via the serial data circuit to the instrument cluster in order to control the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0462 Fuel Level Sensor 1 Circuit Low Voltage
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The engine is running (LG4). |
Conditions for Setting the DTC
| • | The primary fuel level signal on vehicles with dual tanks or the fuel level signal on vehicles with single tank is less than 0.5 volts (LLY and L18). |
| • | The primary fuel level signal on vehicles with dual tanks or the fuel level signal on vehicles with single tank is less than 3.5 percent (LG4). |
| • | The above condition is present for greater than 20 seconds. |
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The PCM records the operating conditions at the time that the diagnostic test fails. The PCM displays the failure information in the Failure Records on the scan tool. |
Conditions for Clearing the DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
| • | The PCM receives the clear code command from the scan tool. |
Diagnostic Aids
| • | Use the Freeze Frame/Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data may help in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also help in determining the number of ignition cycles that the diagnostic test reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, including those for RPM, for engine load, for vehicle speed, for temperature, and for others. This will isolate at what point the DTC failed. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | When the fuel level sensor signal is lower than normal, the Fuel Level Sensor % parameter in the ECM Fuel Data data list on the scan tool indicates a value less than 4% for a single tank (LG4 only). When the primary fuel level sensor signal is lower than normal, the Fuel Level Sensor % parameter in the ECM Fuel Data data list on the scan tool indicates a value about half the actual fuel level for dual tanks (LG4 only). |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Does the scan tool indicate that the Fuel Level Sensor parameter is less than the specified value? | 0.5 V (LLY and L18) 50% (LG4 only) | Go to Step 3 | Go to Diagnostic Aids | ||||||
Does the scan tool indicate that the Fuel Level Sensor parameter is greater than the specified value? | 4.5 V (LLY and L18 only) 98% (LG4 only) | Go to Step 5 | Go to Step 4 | |||||||
4 | Test the signal circuit of the fuel level sensor for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | ||||||
5 | Inspect for poor connections at the harness connector of the fuel level sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||
6 | Inspect for poor connections at the harness connector of the PCM or the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||
7 | Replace the fuel level sensor. Refer to one of the following procedures:
Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
8 | Replace the PCM or ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
