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Electronic Control System Gas Plus Engines – FAULT CODE 1919 – L Gas Plus

Humidity Sensor – Data Erratic, Intermittent, or Incorrect

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Overview

CODE REASON EFFECT
Fault Code: 1919
PID: 
SPN: 2946
FMI: 2
LAMP: Amber
SRT: 

Humidity Sensor – Data erratic, intermittent, or incorrect.

Possible reduced performance.

Humidity Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The ECM uses the humidity sensor to measure relative humidity. The humidity sensor is connected to sensor supply number 1.

Component Location

The humidity sensor is located in the turbocharger compressor inlet elbow.

Shop Talk

Relative humidity is calculated using the turbocharger compressor temperature sensor, turbocharger compressor pressure sensor, and humidity sensor. The units are displayed in grains/pound mass of dry air. The humidity sensor can
only provide a valid reading under certain engine operating conditions. The value displayed for specific humidity is the last value updated by the sensor. A value of 75 grains is the default and will be displayed until the engine operating conditions are met for an update.

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 3164596 – male Framatome test lead

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for sensor supply fault codes. Fault Code 352 or 386 active?
  STEP 1B. Read the fault codes. Fault Code 1919 active?
STEP 2. Check the humidity sensor and circuit.  
  STEP 2A. Inspect the humidity sensor and connector pins. Dirty or damaged pins?
  STEP 2B. Check the sensor supply voltage and return circuit. 4.5 to 5.3 VDC?
  STEP 2C. Check the circuit response. Fault Code 1128 active and Fault Code 1919 inactive?
  STEP 2D. Check the fault codes and verify sensor condition. Fault Code 1919 active?
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 an open circuit in the engine harness. Less than 10 ohms?
  STEP 3D. Check for a pin-to-pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3E. Check for a pin short circuit to ground. Greater than 100k ohms?
  STEP 3F. Check for an inactive fault code. Fault Code 1919 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 1919 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Check for sensor supply fault codes.

Conditions

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

Action

Check for sensor supply fault codes.

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

Fault Codes 352 and/or 386 active?
YES NO
No Repair No Repair
Fault Code 352 and/or 386

Guided Step 1B – Check the fault codes.

Conditions

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

Action

Check the fault code.

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

Fault Code 1919 active?
YES NO
No Repair No Repair

Procedure
019-361

Guided Step 2 – Check the humidity sensor and circuit.

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the humidity sensor from the engine harness.

Action

Inspect the engine harness and humidity sensor connector pins for the following:

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

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

Dirty or damaged pins?
YES NO

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

Clean the connector and pins.

Repair the damaged harness, connector, or pins if possible.

Refer to Procedure
019-043

Refer to Procedure
019-218.

Refer to Procedure
019-356.

 No Repair

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the humidity sensor from the engine harness
  • Turn keyswitch ON.

Action

Check the supply voltage and return circuit.

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

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

4.5 to 5.3 VDC?
YES NO
No Repair No Repair

Guided Step 2C – Check the circuit response.

Conditions

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

Action

Place a jumper wire between the humidity SUPPLY pin and the humidity SIGNAL pin at the humidity sensor connector of the engine harness.

  • Check for the appropriate circuit response after 30 seconds.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 1128 active and Fault Code 1919 inactive?
YES NO
No Repair No Repair

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

Conditions

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

Action

Check for the appropriate circuit response after 30 seconds.

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

Fault Code 1919 active?
YES NO

A malfunctioning sensor has been detected.

Replace the humidity sensor.

Refer to procedure
019-356.

None. The removal and installation of the connector corrected the malfunction.

Guided Step 3 – Check the ECM and engine harness.

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

Conditions

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

Action

Inspect the engine harness and ECM engine harness connector 1 pins for the following:

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

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

Dirty or damaged pins?
YES NO

A damaged connection has been detected in the ECM or engine harness connector.

Clean the connector and pins.

Repair the damaged harness, connector or pins if possible.

Refer to Procedure
019-043.

Refer to Procedure
019-204.

Refer to Procedure
019-031.

 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 humidity sensor from the engine harness.

Action

Check for an open circuit.

  • Measure the resistance between the engine harness ECM engine connector 1 humidity SUPPLY pin and the engine harness humidity sensor connector SUPPLY pin.

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

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

Less than 10 ohms?
YES NO
No Repair

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

Repair or replace the engine harness.

Refer to Procedure
019-204.

Refer to Procedure
019-043.

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

Conditions

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

Action

Check for an open circuit.

  • Measure the resistance between the engine harness ECM engine connector 1 humidity SIGNAL pin and the engine harness humidity sensor connector SIGNAL pin.

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

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

Less than 10 ohms?
YES NO
No Repair

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

Repair or replace the engine harness.

Refer to Procedure
019-204.

Refer to Procedure
019-043.

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connectors 1 and 2 from the ECM
  • Disconnect the humidity sensor from the engine harness.

Action

Check for a pin-to-pin short.

  • Measure the resistance between the humidity SIGNAL pin in the engine harness ECM engine connector 1 and all other pins in the engine harness connector 1.
  • Measure the resistance between the humidity SIGNAL pin in the engine harness ECM engine connector 1 and all other pins in the engine harness connector 2.

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

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

Greater than 100K ohms?
YES NO
No Repair

A pin-to-pin short circuit on the signal line has been detected in the engine harness.

Repair or replace the engine harness.

Refer to Procedure
019-204.

Refer to Procedure
019-043.

Guided Step 3E – Check for a pin short circuit to ground.

Conditions

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

Action

Check for a pin short to ground.

  • Measure the resistance between the humidity SIGNAL pin in the engine harness ECM engine connector 1 and engine block ground

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

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

Greater than 100K ohms?
YES NO
No Repair

A pin to ground short circuit on the signal line has been detected in the engine harness.

Repair or replace the engine harness.

Refer to Procedure
019-204.

Refer to Procedure
019-043.

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

Conditions

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

Action

Check for the appropriate circuit response after 30 seconds.

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

Fault Code 1919 inactive?
YES NO

None. The removal and installation of the connector corrected the malfunction.

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

Disable the fault code.

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

Fault Code 1919 inactive?
YES NO
No Repair

Troubleshooting procedures need to be repeated from the beginning.

Guided Step 4B – Clear the inactive fault codes.

Conditions

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

Action

Clear the inactive fault codes.

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

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting steps
Last Modified:  28-Nov-2006
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