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Electronic Control System Gas Plus Engines – FAULT CODE 238

Sensor Supply Voltage Number 3 Circuit – Shorted Low

Overview

CODE REASON EFFECT
Fault Code: 238
PID: 232
SPN: 620
FMI: 4
LAMP: Amber
SRT: 

Sensor Supply Voltage Number 3 Circuit – Shorted Low. Low voltage detected on sensor supply voltage 12 VDC (3).

Possible reduced performance.

Sensor Supply Voltage Number 3 Circuit
SMALL | MEDIUM | LARGE

Circuit Description

This is the voltage supply for the gas mass flow sensor.

Component Location

The sensor supply circuit number 3 circuit is contained in the engine wiring harness.

Shop Talk

When testing the resistance of the wires, make sure that the ECM and OEM connectors are disconnected.

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 code. Fault Code 238 inactive?
STEP 2. Check the sensors and sensor supply circuit.  
  STEP 2A. Inspect the gas mass flow sensor and connector pins connected to sensor supply number 3. Dirty or damaged pins?
  STEP 2A-1. Check for 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. Greater than 100k ohms?
  STEP 3B-1. Check for a short circuit to ground.
  STEP 3C. Check for an inactive fault code. Fault Code 238 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 238 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 INSITE™ electronic service tool.

Action

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

Fault Code 238 inactive?
YES NO
No Repair No Repair

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

Guided Step 2A – Inspect the gas mass flow sensor and connector pins connected to sensor supply number 3.

Conditions

  • Turn keyswitch OFF
  • Disconnect the gas mass flow sensor from the engine harness.

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.

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 connector.

Repair the damaged pins. Repair or 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.
  • 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 ECM response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the gas mass floe 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 238 active?
YES NO
No Repair

A defective sensor has been detected.

Replace the gas mass flow sensor. Refer to Procedure 019-085.

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 damaged
  • 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 Component Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

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

Repair the damaged pins. Repair or 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.
  • 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 for a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 from the ECM
  • Disconnect the gas mass flow sensor from the engine harness
  • Make sure all components connected to sensor supply number 3 circuit are disconnected.

Action

  • Measure the resistance between the sensor SUPPLY number 3 pin in engine harness ECM connector 1 to all other pins in the engine connector 1.
  • Measure the resistance between the sensor SUPPLY number 3 pin in engine harness ECM connector 1 to all other pins in the engine connector 2.

Greater than 100k ohms?
YES NO
No Repair

A pin to pin short circuit on the sensor supply number 3 circuit line has been detected in the engine harness.

Repair the damaged pins. Repair or 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.
  • 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 1 from the ECM
  • Disconnect the gas mass flow sensor from the engine harness
  • Make sure all components connected to sensor supply number 3 circuit are disconnected.

Action

  • Measure the resistance between the sensor SUPPLY voltage number 3 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 the 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 sensor supply number 3 line has been detected in the engine harness.

Repair the damaged pins. Repair or 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.
  • 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 238 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 the fault code is inactive.

Fault Code 238 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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