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Electronic Control System Gas Plus Engines – FAULT CODE 461 – L Gas Plus

Ignition Reference Signal Circuit – Shorted High

Overview

CODE REASON EFFECT
Fault Code: 461
PID: S66
SPN: 725
FMI: 3
LAMP: Red
SRT: 

Ignition Control Mode (Reference) Signal Circuit – Shorted High. High voltage detected at the ECM.

Engine will die or not start.

Ignition Reference Signal Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The ignition control module (ICM) is a distributorless ignition module that provides a signal to the coils and delivers high voltage to the spark plugs. The electronic control module (ECM) controls the ICM by providing ignition timing information.

Component Location

The ICM is located next to the ECM on the side of the engine.

Shop Talk

For the ICM to operate correctly, all connectors must be clean and tight.

Cautions and Warnings

 WARNING 

EXTREMELY HIGH VOLTAGE. Do not touch any ignition wiring or component while the engine is operating unless an insulated tool is being used to prevent electrical shock and damage to the equipment.
 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.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 461 active?
STEP 2. Check the ignition control module.  
  STEP 2A. Inspect the ICM and engine harness connector pins. Dirty or damaged pins?
  STEP 2B. Read the fault codes. Fault Code 461 active?
STEP 3. Check the engine harness.  
  STEP 3A. Inspect the engine harness and ECM connector pins. Dirty or damaged pins?
  STEP 3B. Check for an open circuit. Less than 10 ohms?
  STEP 3C. Check for a short circuit from pin to pin. Greater than 100k ohms?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 461 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

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

Action

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

Fault Code 461 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the ignition control module.

Guided Step 2A – Inspect the ICM and engine harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the ignition control module.

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.

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

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

Dirty or damaged pins?
YES NO

Repair the damaged pins. Repair or replace the engine harness, or replace the ICM, 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 019-201.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the sensor. Refer to Procedure 019-105.
 No Repair

Guided Step 2B – Read the fault codes.

Conditions

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

Action

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 461 active?
YES NO
No Repair No Repair

Guided Step 3 – Check the engine harness.

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 and connector 2 from the ECM
  • Disconnect the engine harness from the OEM harness at the 23 pin and 31 pin OEM connectors.

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.

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

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

Dirty or damaged pins?
YES NO

Repair the damaged pins. Repair or replace the engine harness, or replace the ECM, 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.
  • Replace the ECM. Call for pre-authorization. Refer to Procedure 019-031.
 No Repair

Guided Step 3B – Check for an open circuit.

Conditions

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

Action

  • Measure the resistance between the ICM SIGNAL reference pin in the engine harness ECM connector to the ICM SIGNAL reference pin in the engine harness ICM connector.

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

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

Less than 10 ohms?
YES NO
No Repair

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 019-201 or 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3C – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the ICM
  • Disconnect the engine harness from the OEM harness at the 23-pin and 31-pin OEM connectors.
  • Disconnect engine harness connector 1 and connector 2 from the ECM.

Action

  • Measure the resistance between the ICM SIGNAL reference pin in engine harness ECM connector 1 to all other pins in the connector.
  • Measure the resistance between the ICM SIGNAL reference pin in engine harness ECM connector 1 to all other pins in engine harness ECM connector 2.

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

For general resistance measurement 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

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 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 461 is inactive.

Fault Code 461 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

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  01-Sep-2004
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