Chevrolet Silverado / GMC Sierra. Service manual — part 2422

Instrument Cluster Schematics

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

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 Testing

1. Ignition OFF, disconnect the harness connector X2 at the ECM.

2. Ignition ON, verify that the wait to start indicator is OFF.

If not the specified value, test the wait to start indicator control signal circuit terminal
16 for a short to ground. If the circuit tests normal, replace the instrument panel cluster
(IPC).

3. Install a 3-amp fused jumper between the wait to start control signal circuit terminal 16 and

ground. Verify that the wait to start indicator is ON.

If not the specified value, test the wait to start indicator control signal circuit terminal
16 for a short to voltage or an open/high resistance. If the circuit tests normal, replace
the IPC.

4. If all circuits test normal, replace the ECM.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for the ECM or IPC replacement, setup, and programming

DTC P0461

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0461

Fuel Level Sensor 1 Performance

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 and evaporative emission (EVAP) diagnostics.

This diagnostic tests for a stuck fuel level sensor signal. The ECM sets this DTC if the fuel level
sensor signal appears to be stuck based on a lack of signal variation expected during normal
operation.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

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

The ECM detects a change in fuel level less than 10 liters (1.3 gallons) over a distance of 241.4
km (150 miles).

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.

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

Component Testing

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

1. Ignition OFF, remove the fuel level sender and verify there are no obstructions interfering

with the fuel level sender.

If any interference is present, repair the fuel sender interference.

2. Ignition OFF, disconnect the harness connector at the fuel level sensor.

3. 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.

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 P0462

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0462

Fuel Level Sensor 1 Low Voltage

Diagnostic Fault Information

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado