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FAULT CODE 243

Engine Brake Supply Circuit

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Overview

CODE REASON EFFECT
Fault Code: 243
PID: P121
SPN: 513
FMI: 4
LAMP: Yellow
SRT: 00-098		 Less than 6 VDC detected at the engine brake supply pin 18 of the actuator harness connector. This indicates a current draw from the electronic control module (ECM) greater than 2 amps or a faulty ECM power supply. The engine brake can not be activated.

Engine Brake Relay Supply Circuit

Circuit Description

The ECM enables the engine brake by sending a signal directly to the engine brakes. The ECM will only enable the engine brakes under certain operating conditions.

Component Location

Refer to the OEM troubleshooting and repair manual for the location of the engine brakes.

Cautions and Warnings

 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.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the engine brake solenoids.
STEP 1A. Inspect the engine brake solenoid and brake harness connector pins. No damaged pins
STEP 1B. Read the fault codes. Fault Code 243 active
STEP 1C. Read the fault codes with brake solenoids disconnected. Fault Code 243 active
STEP 2. Check the engine brake harness.
STEP 2A. Inspect the engine brake harness and engine harness connector pins. No damaged pins
STEP 2B. Read the fault codes. Fault Code 243 active
STEP 2C. Check for a short circuit to ground. More than 100k ohms
STEP 3. Check the actuator harness.
STEP 3A. Inspect the actuator harness and the ECM connector pins. No damaged pins
STEP 3B. Read the fault codes. Fault Code 243 active
STEP 3C. Check for a short circuit between pins. More than 100k ohms
STEP 3D. Check for a short circuit to ground. More than 100k ohms
STEP 4. Clear the fault codes.
STEP 4A. Disable the fault code. Fault Code 243 inactive
STEP 4B. Clear the inactive fault codes. All fault codes cleared

Guided Step 1 – Check the engine brake solenoids.

Guided Step 1A – Inspect the engine brake solenoid and brake harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the brake harness from the engine brake solenoid.
  • Flush and clean the connectors using electronic contact cleaner, Part Number 3824510.

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the engine brake harness. Refer to Procedure 019-201, 019-202, or 019-205.
  • Replace the engine brake harness. Refer to Procedure 019-043.
  • Replace the engine brake solenoid. Refer to the base engine troubleshooting and repair manual.

Guided Step 1B – Read the fault codes.

Conditions

  • Connect the brake harness to the brake solenoids.
  • Turn keyswitch ON.

Action

  • Start the engine and activate the engine brakes.
  • Read the fault codes using INSITE™.
OK NOT OK
Fault Code 243 active Repair complete.

Guided Step 1C – Read the fault codes with brake solenoids disconnected.

Conditions

  • Disconnect the brake harness from the brake solenoids.
  • Turn keyswitch ON.

Action

  • Start the engine, run above 1000 rpm, and activate the engine brakes.
  • Read the fault codes using INSITE™.
OK NOT OK
Fault Code 243 active Replace the engine brake solenoid(s), or repair the engine brake wiring harness between connector and solenoid. Refer to the base engine troubleshooting and repair manual.

Guided Step 2 – Check the engine brake harness.

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

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine brake harness from the engine harness.
  • Flush and clean the connectors using electronic contact cleaner, Part Number 3824510.

Action

  • bent or broken pins
  • pushed back or expanded pins
  • corroded pins
  • moisture in or on the connector
  • missing or damaged seals
  • dirt or debris in or on the connector.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the engine brake harness. Refer to Procedure 019-201, 019-202, or 019-205.
  • Replace the engine brake harness. Refer to Procedure 019-043.
  • Repair the engine harness. Refer to Procedure 019-201, 019-202, or 019-205.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 2B – Read the fault codes.

Conditions

  • Connect the engine brake harness to the engine harness.
  • Turn keyswitch ON.

Action

  • Start the engine, run above 1000 rpm, and activate the engine brakes.
  • Read the fault codes using INSITE™.
OK NOT OK
Fault Code 243 active Fault Code 243 inactive. Repair complete.

 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.
Guided Step 2C – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine brake harness from the engine harness.
  • Disconnect the engine brake harness from the engine brake solenoids.

Action

  • Measure the resistance from pin A of the engine brake harness to engine block ground.
  • Measure the resistance from pin B of the engine brake harness to engine block ground.
OK NOT OK
More than 100k ohms Replace the engine brake harness. Refer to Procedure 019-043.

Guided Step 3 – Check the actuator harness.

 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 3A – Inspect the actuator harness and the ECM connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Repair the actuator harness. Refer to Procedure 019-203.
  • Replace the actuator harness. Refer to Procedure 019-043.
  • Replace the ECM. Refer to Procedure 019-031.
  • Replace the o-ring on the 28-pin connector if it is damaged or missing. Refer to Procedure 019-203.

Guided Step 3B – Read the fault codes.

Conditions

  • Turn keyswitch OFF.
  • Connect all components.

Action

  • Start the engine and let it idle for 1 minute.
  • Read the fault codes using INSITE™.
OK NOT OK
Fault Code 243 active Fault Code 243 inactive. Repair complete.

 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.
Guided Step 3C – Check for a short circuit between pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.
  • Disconnect the engine brake solenoids from the engine brake harness.

Action

  • Measure the resistance from pin 18 to all other pins in the actuator harness connector.
OK NOT OK
More than 100k ohms Replace the actuator harness. Refer to Procedure 019-043.

 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.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 3D – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.
  • Disconnect the actuator harness from the brake harness.

Action

  • Measure resistance from pin 18 in the actuator harness connector to engine block ground.
OK NOT OK
More than 100k ohms

  • Replace the ECM. Refer to Procedure 019-031.
 Replace the actuator harness. Refer to Procedure 019-043.

Guided Step 4 – Clear the fault codes.

 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 4A – Disable the fault code.

Conditions

  • Connect all the components.

Action

  • Start the engine and let it idle for 1 minute.
  • Verify Fault Code 243 is inactive.
OK NOT OK
Fault Code 243 inactive Replace the ECM. Refer to Procedure 019-031.

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all the components.

Action

  • Erase the inactive fault codes using INSITE™.
OK NOT OK
All fault codes cleared Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting chart
Last Modified:  29-Oct-2003
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