3126B and 3126E On-highway Engines Caterpillar

Use this procedure under the following situation:

Use this procedure if one of the following diagnostic codes is present:

• 252-11 Incorrect Engine Software (59)

• 253-02 Check Customer or System Parameters (56)

• 253-14 Truck Manufacturer Parameter Not Programmed (56)

Also, use this procedure if the integrity of the Customer Parameters or the System Parameters in the ECM is questionable. Also, use this procedure if the data for the Engine Lifetime Totals is questionable.

The following background information is related to this procedure:

The Engine Control Module (ECM) is the computer which controls the Caterpillar electronic truck engine. The Personality Module contains the software that controls the operation of the computer (ECM).

The Personality Module software is the instructions that are used by the ECM to control the engine. For this reason, updating the Personality Module to a different version may cause some engine functions to behave in a different manner.

Performance Maps

Performance Maps define characteristics for various operating conditions. These characteristics are used to achieve optimum performance while emissions requirements are being met. Examples of these characteristics are included in the following list:

• Fuel rate

• Timing

These characteristics are programmed into the Personality Module at the factory only.

Microprocessor

The ECM uses a microprocessor to perform the computing that is required to perform the following functions:

• Governing

• Controlling timing

• Generating diagnostic codes

• Communicating with service tools

The microprocessor reads the instructions from the software in the Personality Module.

Programmable Parameters

Programmable Parameters are stored in permanent memory. This includes both Customer Specified Parameters and System Configuration Parameters. Refer to Troubleshooting, "Customer Specified Parameters" for details on Customer Specified Parameters and refer to Troubleshooting, "System Configuration Parameters" for details on System Configuration Parameters.

Illustration 1	g00772334
ECM and harness connectors

Logged Diagnostics

Logged diagnostics are stored by the ECM into memory so a permanent record of the diagnostic code is retained. Logged faults that are not critical are automatically cleared after 100 hours.

Input Circuits

Input circuits filter electrical noise for sensor signals. Also, input circuits protect internal circuits from potentially damaging voltage levels.

Output Circuits

Output circuits provide the voltage or current that is required to energize components that are connected to the ECM.

Power Circuits

Power circuits provide clean stable electrical power to internal circuits and external sensors.

Test Step 1. Inspect Electrical Connectors and Wiring.

1. Thoroughly inspect ECM vehicle harness connector J1/P1 and the battery connections. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on each of the following wires in the ECM connector:
   • Ignition key switch (terminal 70)

   • +Battery (terminals 52 and 53)

   • −Battery (terminals 65 and 67)

   • ATA data link (terminals 8 and 9)

3. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

4. Check the harness and wiring for abrasion and pinch points from the data link connectors back to the ECM.

Expected Result:

All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check for Diagnostic Codes.

Connect ET and check for diagnostic codes.

Expected Result:

Result 1 The following diagnostic code requires troubleshooting:

• 252-11 Incorrect Engine Software (59)

Result 2 The following diagnostic code requires troubleshooting:

• 253-02 Check Customer or System Parameters (56)

Result 3 Scrambled parameters or data require troubleshooting.

Result 4 The following diagnostic code requires troubleshooting:

• 253-14 Truck Manufacturer Programmed Not Programmed (6)

Results:

• Result 1 - Proceed to Test Step 3.

• Result 2 - Proceed to Test Step 4.

• Result 3 - Proceed to Test Step 5.

• Result 4 - Proceed to Test Step 6.

Test Step 3. Use ET To Check The Part Number Of The ECM Personality Module.

1. Connect ET at the cab data link connector.

2. Turn the ignition key switch to the ON position.

3. Read the Customer Specified Parameters. Refer to Troubleshooting, "Programming Parameters".

4. Ensure that the Personality Module Part Number agrees with the original engine arrangement.

Expected Result:

The correct Personality Module is installed in the ECM for the engine.

Results:

• Yes -

  Repair: The diagnostic code 252-11 must be cleared if the correct Personality Module has been installed. Clearing this diagnostic code requires Factory Passwords and resetting the Personality Module Code to zero.

  STOP

• No -

  Repair: Reprogram the ECM with the correct Personality Module. Refer to Troubleshooting, "Flash Programming". Verify that the repair eliminates the problem.

  STOP

Test Step 4. Use ET to Determine Parameters that Require Programming.

1. Connect ET at the cab data link connector.

2. Turn the ignition key switch to the ON position.

3. Check the active diagnostic codes. Note any parameters that are listed in the following active diagnostic code:
   • 253-02 Check Customer or System Parameters (56)

Expected Result:

The ECM allows the parameters that are listed under the following active diagnostic code in the "Active Diagnostic Code" screen to be programmed:

• 253-02 Check Customer or System Parameters (56)

Results:

• Yes -

  Repair: Ensure that the cause of all diagnostic codes is repaired.

  STOP

• No -

  Repair: Temporarily connect a test ECM. Ensure that the test ECM will allow the programming of the Parameters. If the test ECM does not allow the programming of the Parameters, the old ECM is OK. Something is wrong in the vehicle wiring. Check the battery supply circuit to the ECM and repair, as required.Verify that the repair eliminates the problem.

  STOP

Test Step 5. Use ET to Review Parameters and Data.

1. Turn the ignition key switch to the ON position.

2. Check the active diagnostic codes and the logged diagnostic codes by using ET.

3. Review the Customer and System Parameters.

4. Review the Engine Lifetime Totals.

Expected Result:

The parameters and totals are scrambled.

Results:

• Yes -

  Repair: Try to reprogram the suspect parameter or parameters. If the ECM does not maintain the parameters, temporarily connect a test ECM. Ensure that the test ECM will allow the programming of the parameters. If the test ECM does not allow the programming of the parameters, the old ECM is OK. Something is wrong in the vehicle wiring. Check the battery supply circuit to the ECM and repair, as required.Verify that the repair eliminates the problem.

  STOP

• No - The ECM is OK.STOP

Test Step 6. Use ET to Determine Programming Requirements

1. Connect ET to the cab data link connector.

2. Turn the ignition key switch to the ON position.

3. Check for active diagnostic codes.

   Note: If the diagnostic code 253-14 is active, the "Truck Manufacturer" parameter must be programmed.

4. Determine the type of chassis. If the engine is installed in a General Motors chassis, program the "Truck Manufacturer" parameter to GM. For any other chassis, program the parameter to "Other".

   Note: ET will indicate that the communication to the ECM must be reestablished in order for the change in the parameter to take effect.

Expected Result:

There are no active diagnostic codes.

Results:

• Yes - Diagnostic codes are active. Proceed to the appropriate troubleshooting procedure for the active diagnostic code. STOP

• No - The ECM has been properly programmed.STOP