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Electronic Control System Gas Plus Engines – FAULT CODE 115 – L Gas Plus

Engine Speed/Position Sensor Circuit – Both Signals Lost

Overview

CODE REASON EFFECT
Fault Code: 115
PID: P190
SPN: 190
FMI: 2
LAMP: Red
SRT: 

Engine speed/position sensor circuit – both signals lost.

Engine can possibly die or will not start.

Engine Position Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The crankshaft and camshaft engine speed/position sensors provides engine speed and position information to the electronic control module (ECM). The sensor is powered by 5 volts. The sensor generates the signal by sensing movement of target teeth machined into a tone wheel that is mounted to the crankshaft.

Component Location

The crankshaft speed/position sensor is located on the intake side of the engine between number 5 and number 6 cylinders at the crankshaft level. The camshaft speed/position sensor in located on the intake side of the engine above the accessory drive. Refer to Procedure 100-002 for a detailed component location.

Shop Talk

When the intake manifold pressure indicates a vacuum, the engine will be running. Fault Code 115 can become active with the keyswitch on and the engine RPM is zero if the intake manifold pressure indicates a pressure that is different than expected. INSITE™ electronic service tool can be used to compare the intake manifold pressure sensor to the mixer inlet pressure sensor. These two sensors must both be equal and read atmospheric pressure (101.3 kPa [14.7 psia] at sea level) with the keyswitch on and the engine is not running. If these are not equal, it possibly indicates an in-range failure of the intake manifold pressure sensor. The engine will possibly not start if this condition exists.

This fault code is recorded when the ECM does not receive a signal from the crankshaft and camshaft speed sensor, or the signal it receives is degraded.

Possible causes of this fault code include: open circuit on the supply, signal, or return circuits in the sensor, engine harness, or ECM.

Short circuits to ground or return circuits in the sensor, engine harness, or ECM.

Short circuits to a voltage source in the sensor, engine harness, or ECM.

Damage to the sensor target teeth or tone wheel.

If this fault code occurs intermittently, look closely for causes of intermittent harness connections such as loose or worn pins in the engine harness connectors.

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 3823995 – male Weather-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 sensor supply fault codes. Fault Code 352 or 386 active?
  STEP 1B. Check for an inactive fault code. Fault Code 115 inactive?
STEP 2. Check the crankshaft speed/position sensor and circuit.  
  STEP 2A. Inspect the crankshaft speed/position sensor connector pins. Dirty or damaged pins?
  STEP 2B. Inspect the camshaft speed/position sensor connector pins. Dirty or damaged pins?
  STEP 2C. Check the sensor supply voltage and return circuit. 4.75 to 5.25 VDC?
  STEP 2D. Inspect the crankshaft speed/position sensor. Damaged sensor tip?
  STEP 2E. Verify adequate crankshaft speed/position sensor air gap. Distance is between 41.36 mm [1.36 in] and 42.65 mm [1.68 in]?
STEP 3. Check the ECM and engine harness.  
  STEP 3A. Inspect the ECM and engine harness and ECM connector pins. Dirty or damaged pins?
  STEP 3B. Check for an inactive fault code. Fault Code 2119 inactive?
  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 to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3F. Check for a pin short circuit to ground. Greater than 100k ohms?
  STEP 3G. Check for an inactive fault code. Fault Code 115 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 115 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

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

Fault Code 352 or 386 active?
YES NO
No Repair No Repair
Fault Code 352 or 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 115 inactive?
YES NO
No Repair No Repair
Procedure 019-362

Guided Step 2 – Check the crankshaft speed/position sensor and circuit.

Guided Step 2A – Inspect the crankshaft speed/position sensor and connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect crankshaft speed/position 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 Components Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

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

Repair the damaged pins. 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.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the heated oxygen sensor. Refer to Procedure 019-365.
 No Repair

Guided Step 2B – Inspect the camshaft speed/position sensor and connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect camshaft speed/position 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 Components Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

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

Repair the damaged pins. 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.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the heated oxygen sensor. Refer to Procedure 019-365.
 No Repair

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

Conditions

  • Turn keyswitch OFF
  • Disconnect crankshaft speed/position sensor from the engine harness
  • Turn keyswitch ON.

Action

  • Measure the voltage between the crankshaft speed/position SUPPLY pin and the crankshaft speed/position RETURN pin at the crankshaft speed/position sensor connector of the engine harness.

Refer to the circuit diagram or wiring diagram for component pin identification.
SMALL | MEDIUM | LARGE

4.75 to 5.25 VDC?
YES NO
No Repair No Repair

Guided Step 2D – Inspect the crankshaft speed/position sensor.

Conditions

  • Turn keyswitch OFF
  • Remove the crankshaft speed/position sensor from the engine.

Action

  • Damage sensor tip
  • Physical signs of the sensor touching the speed or position teeth.

Damaged sensor tip?
YES NO

A defective sensor has been detected.

Replace the crankshaft speed/position sensor. Refer to Procedure 019-365.

Inspect the crankshaft tone wheel/gear teeth for damage or spinning. Sensor clearance is between 41.36 mm [1.36 in] and 42.65 mm [1.68 in].

Refer to Procedure 001-071 in the Troubleshooting and Repair Manual, C8.3G, C Gas Plus and L Gas Plus Engines, Bulletin 3666206.

 No Repair

Guided Step 2E – Verify adequate crankshaft speed/position sensor air gap.

Conditions

  • Turn keyswitch OFF
  • Remove crankshaft speed/position sensor from the engine.

Action

  • Measure the distance between the sensor mounting surface and the edge of the tone wheel.
SMALL | MEDIUM | LARGE

Distance is between 41.36 mm [1.36 in] and 42.65 mm [1.68 in]?
YES NO
No Repair

Inspect the crankshaft tone wheel/gear teeth for damage or spinning. Refer to Procedure 001-071 in the Troubleshooting and Repair Manual, C8.3G, C Gas Plus and L Gas Plus Engines, Bulletin 3666206.

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 connector 1.

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 Components Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

A defective connection has been detected in the ECM connector 1 or engine harness connector.

Repair the damaged pins. Replace the engine harness.

 No Repair

Guided Step 3B – 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 115 inactive?
YES NO

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

 No Repair

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

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness from the ECM connector 1.
  • Disconnect the crankshaft speed/position sensor from the engine harness.
  • Disconnect the camshaft speed/position sensor from the engine harness.

Action

  • Measure the resistance between the ECM connector 1 RETURN pin and the crankshaft speed/position sensor connector RETURN pin.
  • Measure the resistance between the ECM connector 1 SUPPLY pin and the crankshaft speed/position sensor connector SUPPLY pin.
  • Measure the resistance between the ECM connector 1 SIGNAL pin and the crankshaft speed/position sensor connector SIGNAL pin.
  • Measure the resistance between the ECM connector 1 RETURN pin and the camshaft speed/position sensor connector RETURN pin.
  • Measure the resistance between the ECM connector 1 SUPPLY pin and the camshaft speed/position sensor connector SUPPLY pin.
  • Measure the resistance between the ECM connector 1 SIGNAL pin and the camshaft speed/position sensor connector SIGNAL pin.

Note: Shake and wiggle the harness to determine an intermittent connection.

Shake and wiggle the harness to determine an intermittent connection.

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 return current has been detected in the engine harness.

Repair the damaged pins. 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.
  • Repair the engine harness. Refer to Procedure 019-202.
  • 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 the engine harness from the ECM
  • Disconnect the crankshaft speed/position sensor from the engine harness.
  • Disconnect the camshaft speed/position sensor from the engine harness.

Action

  • Measure the resistance between the crankshaft speed/position SIGNAL pin in the engine harness and all other pins in the engine connector 1.
  • Measure the resistance between the crankshaft speed/position SIGNAL pin in the engine harness connector 1 and all other pins in the engine connector 2.
  • Measure the resistance between the camshaft speed/position SIGNAL pin in the engine harness and all other pins in the engine connector 1.
  • Measure the resistance between the camshaft speed/position SIGNAL pin in the engine harness connector 1 and all other pins in the engine 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

SMALL | MEDIUM | LARGE

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 the damaged pins. 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.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the ECM
  • Disconnect the crankshaft speed/position sensor from the engine harness.
  • Disconnect the camshaft speed/position sensor from the engine harness.

Action

  • Measure the resistance between the crankshaft speed/position sensor 5 volt SUPPLY pin in the engine harness connector 1 and all other pins in the ECM connector 1.
  • Measure the resistance between the crankshaft speed/position sensor 5 volt SUPPLY pin in the engine harness connector 1 and all other pins in the ECM connector 2.
  • Measure the resistance between the camshaft speed/position sensor 5 volt SUPPLY pin in the engine harness connector 1 and all other pins in the ECM connector 1.
  • Measure the resistance between the camshaft speed/position sensor 5 volt SUPPLY pin in the engine harness connector 1 and all other pins in the ECM 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

SMALL | MEDIUM | LARGE

Greater than 100k ohms?
YES NO
No Repair

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

Repair the damaged pins. 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.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the ECM
  • Disconnect the crankshaft speed/position sensor from the engine harness.
  • Disconnect the camshaft speed/position sensor from the engine harness.

Action

  • Measure the resistance between the crankshaft speed/position SIGNAL pin in the engine harness ECM connector 1 and ground.
  • Measure the resistance between the camshaft speed/position SIGNAL pin in the engine harness ECM connector 1 and 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 the damaged pins. 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.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3G – 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 115 inactive?
YES NO

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

Troubleshooting procedures need to be repeated from the beginning.

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON or Run/Stop switch to the RUN position
  • 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 115 inactive?
YES NO
No Repair No Repair

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON or Run/Stop switch to the RUN position
  • 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:  28-Sep-2004
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