Chevrolet Silverado / GMC Sierra. Service manual — part 2433

2. Ignition OFF, test for less than 1.0 ohm between the primary fuel level sensor low reference

circuit terminal B and ground.

If greater than the specified range, test the low reference circuit for an open/high
resistance. If the circuit tests normal, replace the ECM.

3. Ignition OFF, test for less than 1.0 ohm between the secondary fuel level sensor low

reference circuit terminal B and ground.

If greater than the specified range, test the low reference circuit for an open/high
resistance. If the circuit tests normal, replace the ECM.

4. Jumper the primary fuel level sensor signal circuit terminal C to secondary fuel level sensor

signal circuit terminal C. Install a Signal Generator and Instrument Panel Tester between the
jumped signal circuits and ground.

5. Ignition ON, vary the signal generator resistance between 40-250 ohms. Verify that the scan

tool Fuel Tank Level Remaining parameter displays a range that varies between 5 and 95
percent as the signal generator resistance changes.

If not within the specified range, test both signal circuits for an open/high resistance. If
the circuits test normal, replace the ECM.

6. Vary the signal generator resistance between 40-250 ohms. Verify that the fuel gage

displays a range that varies between empty and full as the signal generator resistance
changes.

If the gage is incorrect, replace the IPC.

7. If all circuits test normal, perform the fuel level sensor component test before replacing

either the primary or secondary fuel level sensor.

Component Testing

1. Ignition OFF, remove the primary and secondary fuel level senders.

2. While sweeping the primary 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 primary fuel level sensor.

3. While sweeping the secondary 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 secondary fuel level sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

2008 Chevrolet Silverado 1500

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

Silverado

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 the ECM or IPC replacement, setup, and programming

HOURMETER INACCURATE OR INOPERATIVE

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.

Circuit/System Description

The instrument panel cluster (IPC) can display the accumulated engine run time hours when the
cluster is in the OFF AWAKE or ACC, RAP and in the RUN positions. The IPC stores the
accumulated engine run time hours in a non-volatile format. The hourmeter will update every 6
minutes and will not change if the battery is disconnected or removed.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

2008 Chevrolet Silverado 1500

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

Silverado

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

With the engine running, verify that the time on the hourmeter increments properly.

If the time does not increment properly, replace the IPC.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Instrument Cluster Description and Operation

Control Module References for IPC replacement, setup, and programming

INSTRUMENT CLUSTER INOPERATIVE

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.

Circuit/System Description

Voltage is supplied to the instrument panel cluster (IPC) through the battery voltage circuit and
the RUN/CRANK relay voltage circuit. The IPC will operate when the RUN/CRANK relay
voltage circuit is commanded on in the RUN/START position.

Reference Information

Schematic Reference

2008 Chevrolet Silverado 1500

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

Silverado

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 Testing

1. Ignition OFF, disconnect the IPC.

2. Ignition ON, verify that a test lamp illuminates between the following appropriate

RUN/CRANK relay voltage circuit and a ground.

Terminal 2 Cadillac

Terminal 5 Chevrolet/GMC

If the test lamp does not illuminate, repair the RUN/CRANK voltage circuit for a short
to ground or an open/high resistance.

3. Verify that a test lamp illuminates between the following appropriate RUN/CRANK relay

voltage circuit and appropriate IPC ground circuit.

Terminal 2 and 5 Cadillac

Terminal 5 and 13 Chevrolet/GMC

If the test lamp does not illuminate, repair the IPC ground circuit for an open/high
resistance.

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

Repair Procedures

2008 Chevrolet Silverado 1500

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

Silverado