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Electronic Control System Gas Plus Engines – FAULT CODE 263

Fuel Temperature Sensor Circuit – Shorted High

Overview

CODE REASON EFFECT
Fault Code: 263
PID: P174
SPN: 174
FMI: 3
LAMP: Amber
SRT: 

Fuel Temperature Sensor Circuit – Shorted High. Open circuit detected on the signal pin of the ECM.

Possible reduced performance.

Fuel Temperature Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

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

Component Location

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

Shop Talk

The fuel pressure/temperature sensor measures secondary fuel pressure and temperature at the mixer housing after the low-pressure regulator.

All temperature sensors:

  • The resistance of the sensor varies with temperature. The reading you observe should compare to the following table if the sensor is functioning properly.
Temperature (°C) Temperature [°F] Resistance (ohms)
0 32 30k to 36k
25 77 9k to 11k
50 122 3k to 4k
75 167 1350 to 1500
100 212 600 to 675
  • This fault code can log in extremely cold weather.

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 3823996 – female Weather-Pack test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for an inactive fault code. Fault Code 263 inactive?
STEP 2. Check the fuel temperature sensor and circuit.  
  STEP 2A. Inspect the fuel temperature sensor and connector pins. Dirty or damaged pins?
  STEP 2B. Check the sensor resistance. 175 ohms to 274k ohms?
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 3B-1. Check for an open circuit in the engine harness.
  STEP 3C. Check for a pin to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3D. Check for an inactive fault code. Fault Code 263 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 263 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – 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 Codes 263 inactive?
YES NO
No Repair No Repair

Guided Step 2 – Check the fuel temperature sensor and circuit.

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

Conditions

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

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damaged
  • 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 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 harness. Refer to Procedure 019-202.
  • Replace the harness. Refer to Procedure 019-043.
No Repair

Guided Step 2B – Check the sensor response.

Conditions

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

Action

  • Measure the resistance between the SIGNAL pin and RETURN pin at the temperature sensor connector.

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

175k ohms to 274k ohms?
YES NO
No Repair

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

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 engine harness 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 connector.

Repair the damaged pins. Repair or replace the 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 harness. Refer to Procedure 019-204.
  • Replace the 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 from the ECM.
  • Disconnect the fuel temperature sensor from engine harness.

Action

  • Measure the resistance from the fuel temperature RETURN pin in the ECM connector 1 RETURN pin.

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

For general resistance measurement 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 circuit has been detected in the engine harness.

Repair or replace the engine harness.

  • Repair the engine harness. Refer to Procedure 019-202.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3B-1 – Check for an open circuit in the engine harness.

Conditions

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

Action

  • Measure the resistance from the fuel temperature SIGNAL pin in the ECM connector 2 SIGNAL pin.

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

For general resistance measurement 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 circuit has been detected in the engine harness.

Repair or replace the engine harness.

  • Repair the engine harness. Refer to Procedure 019-202.
  • 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 from the ECM.
  • Disconnect the fuel temperature sensor from the engine harness.

Action

  • Measure the resistance from the fuel temperature SIGNAL pin in engine harness and all other pins in the ECM connector 2.
  • Measure the resistance from the fuel temperature SIGNAL pin in engine harness and all other pins in the ECM connector 1.

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

For general resistance measurement 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 SIGNAL line has been detected in the engine harness.

Repair or replace the engine harness.

  • Repair the engine harness. Refer to Procedure 019-202.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3D – 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 Codes 263 inactive?
YES NO
No Repair

Replace the ECM. Call for pre-authorization. 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 that the fault code is inactive.

Fault Code 263 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:  27-Aug-2004
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