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Electronic Control System Gas Plus Engines – FAULT CODE 176

Electronic Throttle Control Actuator Circuit – Shorted Low

Overview

CODE REASON EFFECT
Fault Code: 176
PID: S58
SPN: 698
FMI: 4
LAMP: Red
SRT: 

Electronic Throttle Control Actuator Circuit – Shorted Low. Low voltage detected on the throttle actuator signal pin at the ECM.

Possible reduced performance. Engine can die or not start.

Electronic Throttle Control Actuator Circuit
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Circuit Description

The electronic control module (ECM) controls the electronic throttle control actuator; it is both an input and output device.

Component Location

The electronic throttle control actuator is located after the fuel housing and before the intake manifold inlet.

Shop Talk

The electronic throttle control actuator is a pulse-width modulated component on Gas Plus technology. Within the actuator is the throttle position sensor circuit. This is a non repairable sensor and requires replacement of the actuator upon failure.

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.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 175 active?
STEP 2. Check the electronic throttle control actuator.  
  STEP 2A. Inspect the electronic throttle control actuator and engine harness connector pins. Dirty or damaged pins?
  STEP 2B. Read the fault codes. Fault Code 175 active?
STEP 3. Check the engine harness.  
  STEP 3A. Inspect the engine harness and the 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 to ground. Greater than 100k ohms?
  STEP 3D. 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 176 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 INSITE™ electronic service tool.

Action

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

Fault Code 176 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the electronic throttle control actuator.

Guided Step 2A – Inspect the electronic throttle control actuator and engine harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the electronic throttle control actuator.

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 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 019-201.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the sensor. Refer to Procedure 019-097.
 No Repair

Guided Step 2B – Read the fault codes.

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 read the fault codes.

Fault Code 175 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 from the ECM.

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 electronic throttle control actuator.
  • Disconnect the engine harness from the ECM.

Action

  • Measure the resistance between the throttle actuator positive (+) pin in the engine harness connector to the throttle actuator positive (+) pin in the engine harness actuator connector.
  • Measure the resistance between the throttle actuator negative (-) pin in the engine harness connector to the throttle actuator (-) pin in the engine harness actuator 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 to ground.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the electronic throttle control actuator.
  • Disconnect the engine harness from the ECM.

Action

  • Measure the resistance between the throttle actuator positive (+) pin in the engine harness ECM connector to engine block ground.
  • Measure the resistance between the throttle actuator negative (-) pin in the engine harness ECM connector to engine block ground.

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

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

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the electronic throttle control actuator.
  • 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 throttle actuator positive (+) pin in engine harness ECM connector 1 to all other pins in the connector.
  • Measure the resistance between the throttle actuator negative (-) pin in engine harness ECM connector 1 to all other pins in the connector.
  • Measure the resistance between the throttle actuator positive (+) pin in engine harness ECM connector 1 to all pins in engine harness ECM connector 2.
  • Measure the resistance between the throttle actuator negative (-) pin in engine harness ECM connector 1 to all 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 175 is inactive.

Fault Code 176 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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