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Electronic Control System Gas Plus Engines – FAULT CODE 187

Sensor Supply Voltage 5 Volt (2) Circuit – Shorted Low

Overview

Sensor Supply Voltage 5 Volt (2) Circuit – Shorted Low

CODE REASON EFFECT
Fault Code: 187
PID: S232
SPN: 1080
FMI: 4
LAMP: Yellow
SRT: 

Sensor Supply Voltage (2) Circuit – Shorted Low.

Possible reduced performance.

Sensor Supply Voltage 5 Volt (2) Circuit
SMALL | MEDIUM | LARGE

Circuit Description

This circuit is the voltage supply for the remote accelerator pedal position sensor, mixer inlet pressure sensor, coolant level sensor and coolant pressure/temperature sensor.

Component Location

The sensor supply voltage 5 Volt (2) circuit is contained in the wiring harness.

Shop Talk

The voltage supplies on the B and C Plus engines are broken up into 1, 2, 3, and 4. On the L Gas Plus engine, voltage supplies are broken up into 1, 2 and 4.

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 lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for an inactive fault codes. Fault Codes 187 inactive?
STEP 2. Check the sensors and sensor supply circuit.  
  STEP 2A. Inspect the remote accelerator pedal position sensor and connector pins connected to sensor supply number 2. Dirty or damaged pins?
  STEP 2A-1. Check the circuit response
  STEP 2B. Inspect the mixer inlet pressure sensor and connector pins connected to sensor supply number 2. Dirty or damaged pins?
  STEP 2B-1. Check the circuit response
  STEP 2C. Inspect the coolant level sensor and connector pins connected to sensor supply number 2. Dirty or damaged pins?
  STEP 2C-1. Check the circuit response
  STEP 2D. Inspect the coolant pressure/temperature sensor and connector pins connected to sensor supply number 2. Dirty or damaged pins?
  STEP 2D-1. Check the circuit response
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 a pin to pin short circuit in the engine harness. More than 100k ohms?
  STEP 3B-1. Check for a pin short to ground.
  STEP 3C. Check for an inactive fault code. Fault Code 187 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Codes 187 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 the INSITE™ electronic service tool.

Action

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

Dirty or damaged pins?
YES NO
No Repair No Repair

Guided Step 2 – Check the sensors and sensor supply circuit.

Guided Step 2A – Inspect the remote accelerator pedal position sensor and connector pins connected to sensor supply number 2.

Conditions

  • Turn keyswitch OFF
  • Disconnect the remote accelerator pedal position sensor from the OEM 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 damaged
  • 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 connection.

Repair or replace the engine harness, or replace the sensor, 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 2A-1 – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the remote accelerator pedal position sensor from the OEM harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

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

Fault Code 187 active?
YES NO
No Repair

A defective sensor has been detected.

Replace the remote accelerator pedal position sensor. Refer to Procedure 019-085.

Guided Step 2B – Inspect the mixer inlet pressure sensor and connector pins connected to sensor supply number 2.

Conditions

  • Turn keyswitch OFF
  • Disconnect the mixer inlet 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 damaged
  • 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 connection.

Repair or replace the engine harness, or replace the sensor, 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-1 – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the mixer inlet 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 187 active?
YES NO
No Repair

A defective sensor has been detected.

Replace the mixer inlet pressure sensor. Refer to Procedure 019-098.

Guided Step 2C – Inspect the coolant level sensor and connector pins connected to sensor supply number 2.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant level sensor from the OEM 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 damaged
  • 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 connection.

Repair or replace the engine harness, or replace the sensor, 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 2C-1 – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant level 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 187 active?
YES NO
No Repair

A defective sensor has been detected.

Replace the coolant level sensor. Refer to the OEM troubleshooting and repair manual.

Guided Step 2D – Inspect the coolant pressure/temperature sensor and connector pins connected to sensor supply number 2.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant pressure/temperature 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 damaged
  • 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 connection.

Repair or replace the engine harness, or replace the sensor, 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 2D-1 – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant pressure/temperature 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 187 active?
YES NO
No Repair

A defective sensor has been detected.

Replace the coolant pressure/temperature sensor. Refer to Procedure 019-157.

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 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 damaged
  • 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 engine connector or engine harness connector.

Repair or replace the engine harness, or replace the sensor, 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 doe a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 2 from the ECM
  • Disconnect the remote accelerator pedal position sensor, mixer inlet pressure sensor, coolant level sensor and coolant pressure/temperature sensor from the engine harness.
  • Make sure all components connected to sensor supply number 2 are disconnected.

Action

  • Measure the resistance between the sensor SUPPLY number 2 pin in the engine harness ECM connector 2 and all other pins in the engine connector 2.
  • Measure the resistance between the sensor SUPPLY number 2 pin in the engine harness ECM connector 2 and all other pins in the engine connector 1.

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

For general resistance measurement techniques, refer to 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 sensor supply line number 2 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 3B-1 – Check for a pin short circuit to ground.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 2 from the ECM
  • Disconnect the remote accelerator pedal position sensor, mixer inlet pressure sensor, coolant level sensor and coolant pressure/temperature sensor from the engine harness.
  • Make sure all components connected to sensor supply number 2 are disconnected.

Action

  • Measure the resistance between the sensor SUPPLY number 2 pin in the engine harness ECM connector 2 and ground.

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

For general resistance measurement techniques, refer to 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 sensor supply line number 2 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 3C – 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 187 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 Fault Code 187 inactive.

Fault Code 187 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:  30-Sep-2004
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