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Chevrolet Silverado / GMC Sierra. Manual - part 2423
Circuit/System Description
The fuel level sensor changes resistance in response to the fuel level. The engine control module
(ECM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level.
When the fuel tank is full, the sensor resistance is low and the ECM senses a low signal voltage.
When the fuel tank is empty, the sensor resistance is high and the ECM senses a high signal
voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the
percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via GMLAN
serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information
is also used for misfire, evaporative emission (EVAP), and other onboard diagnostics.
Conditions for Running the DTC
The ignition is ON, with the engine running.
The system voltage is between 11-18 volts.
Conditions for Setting the DTC
The sender output is less than 0.5 volt.
The above condition is present for greater than 30 seconds.
Action Taken When the DTC Sets
The fuel gage defaults to empty.
The low fuel indicator illuminates.
The ECM records the operating conditions at the time that the diagnostic test fails. The
ECM 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.
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Fuel Level Sensor Signal
P0462
1
P0463,
P0464
P0463
P0461
Fuel Level Sensor Low
Reference
-
1
P0463,
P0464
P0463
P0461
1. Fuel Gage Inaccurate or Inoperative
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Diagnostic Aids
A defective fuel level sensor most likely will not set DTC P0462. The sensor has a 500 ohm
default resistor that will prevent it from meeting the code setting criteria of this DTC. Look for
problems in the wiring and in the inline and harness connectors at the sensor and ECM.
Reference Information
Schematic Reference
Instrument Cluster Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Verification
Ignition ON, verify the scan tool Fuel Tank Level Remaining parameter is between 4-98 percent.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition ON, verify that the scan tool Fuel Tank Level Remaining parameter display is less
than 4 percent.
If greater than the specified range, test the signal circuit terminal C for a short to
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
ground. If the circuit tests normal, replace the ECM.
3. If all circuits test normal, test or replace the fuel level sensor.
Component Testing
1. Ignition OFF, remove the fuel level sender.
2. While sweeping the fuel level sensor through its full range of motion, test for a minimum
resistance value of less than 41 ohms and a maximum value greater than 119 ohms between
the signal terminal C and the low reference terminal B.
If not within the specified range, replace the fuel level sensor.
Component Testing
1. Ignition OFF, disconnect the harness connectors at the fuel level sensor.
2. While sweeping the fuel level sensor through its full range of motion, test for a minimum
value less than 41 ohms and a maximum value greater than 119 ohms between the signal
terminal C and the low reference terminal B.
If not within the specified range, replace the fuel level sensor.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Fuel Level Sensor Replacement (Extended Cab w/26 Gal Tank) or Fuel Level Sensor
Replacement (Regular Cab w/34 Gal Tank) or Fuel Level Sensor Replacement
(Regular Cab w/26 Gal Tank) for the 4.3L engine
Fuel Level Sensor Replacement (15 Reg Cab w/26 gal Tank) or Fuel Level Sensor
Replacement (15 Ext/Crew Cab w/26 gal Tank) or Fuel Level Sensor Replacement
(25 Ext/Crew Cab w/26 gal Tank) or Fuel Level Sensor Replacement (15/25
Reg/Ext/Crew Cab w/34 gal Tank) or Fuel Level Sensor Replacement (35
Reg/Ext/Crew Cab w/34 gal Tank) for the 4.8L, 5.3L, 6.0L, and 6.2L engines
Fuel Level Sensor Replacement (Cab/Chassis - Rear Tank) for the 6.6L engine
Control Module References for ECM replacement, setup, and programming
DTC P0463
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0463
Fuel Level Sensor 1 High Voltage
Diagnostic Fault Information
Circuit/System Description
The fuel level sensor changes resistance in response to the fuel level. The engine control module
(ECM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level.
When the fuel tank is full, the sensor resistance is low and the ECM senses a low signal voltage.
When the fuel tank is empty, the sensor resistance is high and the ECM senses a high signal
voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the
percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via GMLAN
serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information
is also used for misfire, evaporative emission (EVAP), and other on-board diagnostics.
Conditions for Running the DTC
The ignition is ON, with the engine running.
The system voltage is between 11-18 volts.
Conditions for Setting the DTC
The sensor output is greater than 3.5 volts.
The above condition is present for greater than 30 seconds.
Action Taken When the DTC Sets
The fuel gage defaults to empty.
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Fuel Level Sensor Signal
P0462
1
P0463,
P0464
P0463
P0461
Fuel Level Sensor Low
Reference
-
1
P0463,
P0464
P0463
P0461
1. Fuel Gage Inaccurate or Inoperative
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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