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Electronic Control System Gas Plus Engines – FAULT CODE 546

Fuel Pressure Sensor Circuit, Secondary- Shorted High

Overview

CODE REASON EFFECT
Fault Code: 546
PID: P94
SPN: 94
FMI: 3
LAMP: Amber
SRT: 

Fuel Pressure Sensor Circuit, Secondary- Shorted High. High voltage detected at the ECM.

Possible reduced performance.

Fuel Pressure/Temperature Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) uses the fuel pressure/temperature sensor to measure the secondary fuel pressure to the engine.

Component Location

The fuel pressure/temperature sensor, secondary, is located in the fuel housing.

Shop Talk

The fuel pressure/temperature sensor measures the secondary fuel pressure to the engine. This is after the low-pressure regulator. The fuel pressure/temperature sensor, secondary, is an absolute sensor.

Cautions and Warnings

 CAUTION 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead
Part Number 3823993 – male Deutsch test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for Fault Code 386. Fault Code 386 active?
  STEP 1B. Check for an inactive fault code. Fault Code 386 inactive?
STEP 2. Check the fuel pressure sensor and circuit.  
  STEP 2A. Inspect the fuel pressure sensor and connector pins. Dirty or damaged pins?
  STEP 2B. Check the circuit response. Fault Code 547 active and Fault Code 546 inactive?
  STEP 2C. Check the sensor supply voltage and return circuit. 4.5 to 5.25 VDC?
  STEP 2D. Check the fault codes and verify sensor condition. Fault Code 546 inactive?
STEP 3. Check the ECM and engine harness.  
  STEP 3A. Inspect the ECM and engine harness connector pins. Dirty or damaged pins?
  STEP 3B. Check for an open circuit in the engine harness. Less than 10 ohms?
  STEP 3C. Check for a pin to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3D. Check for a pin to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3E. Check for an inactive fault code. Fault Code 546 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 546 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Check for Fault Code 386.

Conditions

  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 386 active?
YES NO
No Repair No Repair
Fault Code 386

Guided Step 1B – Check for an inactive fault code.

Conditions

  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 546 inactive?
YES NO
No Repair No Repair

Guided Step 2 – Check the fuel pressure sensor and connector pins.

Guided Step 2A – Inspect the fuel pressure sensor and connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the fuel pressure sensor from the engine harness .

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damage
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Connector shell broken
  • Dirt or debris in or on the connector pins.

For general inspection techniques refer to Component Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

A defective connection has been detected in the sensor or harness connector.

Repair the damaged pins. Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
No Repair

Guided Step 2B – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the fuel pressure sensor from the engine harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 547 active and Fault Code 546 inactive?
YES NO
No Repair No Repair

Guided Step 2C – Check the sensor supply voltage and return circuit.

Conditions

  • Turn keyswitch OFF
  • Disconnect the secondary fuel pressure sensor from the engine harness.
  • Turn keyswitch ON.

Action

  • Measure the voltage between the fuel pressure sensor SUPPLY pin and the fuel pressure RETURN pin at the fuel pressure sensor connector of the engine harness.

Refer to the circuit diagram or wiring diagram for connector pin identification.

4.5 to 5.25 VDC?
YES NO
No Repair No Repair

Guided Step 2D – Check the fault codes and verify sensor condition.

Conditions

  • Turn keyswitch OFF
  • Connect the fuel pressure sensor to the engine harness.
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 546 active?
YES NO

A defective sensor has been detected.

Replace the fuel pressure sensor. Refer to Procedure 019-153.

 No Repair

Guided Step 3 – Check the ECM and engine harness.

Guided Step 3A – Inspect the ECM and engine harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 and connector 2 from the ECM.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damage
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Connector shell broken
  • Dirt or debris in or on the connector pins.

For general inspection techniques refer to Component Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

A defective connection has been detected in the ECM or engine harness connectors.

Repair the damaged pins. Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
No Repair

Guided Step 3B – Check for an open circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 from the ECM
  • Disconnect the fuel pressure sensor from the engine harness.

Action

  • Measure the resistance between the fuel pressure sensor RETURN pin in the engine harness connector 1 and the engine harness fuel pressure sensor connector RETURN pin.

Refer to the circuit diagram or wiring diagram for connector pin identification.

For general resistance measurements techniques refer to the Resistance Measurements Using a Multimeter and Wiring Diagram, Procedure 019-360.

Less than 10 ohms?
YES NO
No Repair

An open return circuit has been detected in the engine harness.

Repair or replace the engine harness.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3C – Check for a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 1 and connector 2 from the ECM.
  • Disconnect the fuel pressure sensor from the engine harness.

Action

  • Measure the resistance between the fuel pressure SIGNAL pin in engine harness connector 1 to all other pins in the engine connector 1.
  • Measure the resistance between the fuel pressure SIGNAL pin in engine harness connector 1 to all other pins in the engine harness connector 2.

Refer to the circuit diagram or wiring diagram for connector pin identification.

For general resistance measurements techniques refer to the Resistance Measurements Using a Multimeter and Wiring Diagram, Procedure 019-360.
SMALL | MEDIUM | LARGE

Greater than 100k ohms?
YES NO
No Repair

An pin to pin short circuit on the SIGNAL line has been detected in the engine harness.

Repair or replace the engine harness.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3D – Check for a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 1 and connector 2 from the ECM.
  • Disconnect the fuel pressure sensor from the engine harness.

Action

  • Measure the resistance between the fuel pressure SUPPLY pin in engine harness connector 1 to all other pins in the engine connector 1.
  • Measure the resistance between the fuel pressure SUPPLY pin in engine harness connector 1 to all other pins in the engine harness connector 2.

Refer to the circuit diagram or wiring diagram for connector pin identification.

For general resistance measurements techniques refer to the Resistance Measurements Using a Multimeter and Wiring Diagram, Procedure 019-360.

Greater than 100k ohms?
YES NO
No Repair

An pin to pin short circuit on the SUPPLY line has been detected in the engine harness.

Repair or replace the engine harness.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3E – Check for an inactive fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 546 inactive?
YES NO
No Repair

Replace the ECM. Call for pre-authorization.

Replace the ECM. Refer to Procedure 019-031.

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to verify the fault code is inactive.

Fault Code 546 inactive?
YES NO
No Repair No Repair

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to erase the inactive fault codes.

All fault codes cleared?
YES NO
No Repair No Repair
Repair complete
Appropriate troubleshooting charts
Last Modified:  17-Aug-2004
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