Chevrolet Silverado / GMC Sierra. Service manual — part 2426

resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and

ground.

If less than the specified range, test the 5-volt reference circuit for a short to ground or
an open/high resistance. If the circuit tests normal, replace the ECM.

If greater than the specified range, test the 5-volt reference circuit for a short to
voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 8 kPa (1.2 psi).

If greater than the specified range, test the signal circuit terminal 3 for a short to
voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference

circuit terminal 2. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than
550 kPa (80 psi).

If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the EOP sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Oil Pressure Sensor and/or Switch Replacement for the 4.3L engine

Engine Oil Pressure Sensor and/or Switch Replacement for the 4.8L, 5.3L, 6.0L, and
6.2L engines

Engine Oil Pressure Sensor and/or Switch Replacement for the 6.6L engine

Control Module References for ECM replacement, setup, and programming

DTC P2066

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 P2066

2008 Chevrolet Silverado 1500

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

Silverado

Fuel Level Sensor 2 Performance

Diagnostic Fault Information

Circuit/System Description

The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel
level. The engine control module (ECM) monitors the signal circuits of the primary fuel level
sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank
is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage
on both the signal circuits of the primary fuel level sender and the secondary fuel level sender.
When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM
senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and
the secondary fuel level sender 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.

Fuel level is greater than 32 liters (8.5 gallons).

Conditions for Setting the DTC

The ECM detects a change in fuel level less than 3 liters (0.8 gallon) over a distance greater
than 282 km (175 miles).

The vehicle is at rest and the primary fuel tank increases by 3 liters (0.8 gallon) and the
secondary fuel tank does not decrease by 3 liters (0.8 gallon) when the transfer pump is on

Circuit

Short to

Ground

High

Resistance

Open

Short to

Voltage

Signal

Performance

Fuel Level Sensor Signal
Secondary

P2067

1

P2068

P2068

P2066

Fuel Level Sensor Low
Reference

-

1

P2068

P2068

P2066

1. Fuel Gage Inaccurate or Inoperative

2008 Chevrolet Silverado 1500

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

Silverado

greater than 500 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.

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 secondary 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 secondary 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 secondary 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 P2067

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 P2067

Fuel Level Sensor 2 Low Voltage

Diagnostic Fault Information

2008 Chevrolet Silverado 1500

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

Silverado