Fuel Gauge Inaccurate or Inoperative (with LC8 and KO7)

Fuel Gauge Inaccurate or Inoperative (with LC8 and KO7)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The liquid propane gas control module monitors the signal of the of the primary fuel level sensor to determine the amount of liquid propane in the tank. The liquid propane gas control module uses this signal in order to calculate the percentage of remaining liquid propane gas in the tank and converts it to a PWM signal sent to the ECM. The ECM sends the fuel level percentage via the serial data to the instrument cluster in order to control the fuel gauge. The secondary fuel level sensor is only used as a input to the liquid propane gas control module to transfer fuel to the primary tank.

Reference Information

Schematic Reference

Instrument Cluster Schematics Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

Instrument Cluster Description and Operation Instrument Cluster

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the scan tool ECM - Fuel Level Sensor parameters. The reading should be between 0.5-3.5 V and vary with fuel level.

2. Ignition ON, perform the Instrument Cluster Gauge Sweep test with the scan tool, verify that the fuel level gauge sweeps from its low to high position.

• If the fuel level gauge does not sweep, replace the instrument cluster.

Circuit/System Testing

Note:
The secondary fuel level sensor is only used as a input to the liquid propane gas control module to transfer fuel to the primary tank.

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

2. Test for less than 10 ohms between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the LPG Control Module.

• 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 LPG control module.

4. Ignition OFF, disconnect the harness connector at the LPG control module.

5. Ignition ON, test for 4.0-6.0V between the signal circuit terminal C2 and ground.

• 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.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

• If within specified range, replace the LPG control module.

6. If all circuits test normal, replace the fuel level sensor-primary.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Compressed Natural Gas Control Module Replacement Service and Repair

* Control Module References Control Module References for the ECM, LPG control module and IPC replacement, programming and setup