G3520B Industrial Engine Caterpillar

Electronic control modules contain no moving parts. Replacement of an electronic control module (ECM) can consume much time. Before you replace an ECM, follow the troubleshooting procedures in this manual in order to be sure that replacement of the ECM will correct the problem.

Note: The master ECM and the slave ECM should not be interchanged in order to determine if an ECM is faulty. If the master ECM and the slave ECM are interchanged, all of the configuration data for each ECM must be transferred into the Caterpillar Electronic Technician (ET). The appropriate configuration data must then be re-entered into the appropriate ECM. Failure to program each ECM correctly may result in improper engine operation.

Verify that the suspect ECM is the cause of the problem. Install a test ECM in place of the suspect ECM. Transfer the software from the suspect ECM to the test ECM. Program all the parameters for the test ECM in order to match the parameters of the suspect ECM. The parameters must match. Refer to the following test steps for details on programming the parameters.

If the test ECM resolves the problem, reconnect the suspect ECM. Verify that the problem recurs. If the problem recurs, replace the suspect ECM with the test ECM.

Note: If the parameters cannot be read from the suspect ECM, the parameters must be obtained from records or from the factory.

Perform the following procedure to replace the ECM.

1. Use the "Service/Copy Configuration/ECM Replacement" function of Cat ET.

   Save the file. You can select "Load from ECM". You may also select the "Print" function in order to obtain a paper copy of the parameter settings.

   Note: Before you replace an ECM, record all of the logged events.

   1. Connect Cat ET with the communications adapter. Select "Service/Copy Configuration/ECM Replacement" from the drop-down menu on Cat ET.

      Cat ET will load the configuration parameters and the monitoring system parameters of the suspect ECM.

   2. Select "Load from ECM" in the lower left corner of the Cat ET screen. Select the suspect ECM and select "OK".

      After the loading is complete, the Cat ET will display this message: "The data has been successfully loaded from the ECM". Select "OK".

   3. Select "File/Disconnect F8" from the drop-down menu.

Note: Do not terminate Cat ET.

2. Replace the ECM.

   1. Set the engine control to the "OFF/RESET" mode.
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   Illustration 1	g01095860
   The terminal box for the master ECM is shown. The terminal box for the slave ECM is similar. (1) Ground strap (2) ECM connector (3) ECM connector

   2. Remove the electrical power from the engine.

   3. Use a 4 mm allen wrench to disconnect connectors (2) and (3) .

   4. Remove the mounting nut in order to disconnect ground strap (1). Remove the three remaining mounting nuts.

   Note: Rubber grommets behind the ECM are held in place by the mounting studs. The grommets help to reduce vibration. The grommets may fall when the ECM is removed. Be sure not to lose the grommets.

   5. Remove the ECM from the terminal box.

3. Install the replacement ECM.

   1. Use the mounting hardware to install the new ECM. Use a mounting nut to fasten the ground strap for the ECM to the upper left mounting stud. Then install the other three mounting nuts.

      Check the mounting hardware and the ECM for correct installation. A correctly installed ECM will move slightly on the rubber grommets. If the ECM cannot move slightly on the grommets, check that the washers, spacers, and grommets are positioned correctly.

   2. Use a 4 mm allen wrench to connect the P1 and P2 connectors to the ECM. Tighten the screws to a torque of 6 ± 1 N·m (55 ± 9 lb in).

4. Program the configuration parameters and the monitoring system parameters into the replacement ECM.

   1. Restore the electrical power to the engine.

   2. Set the engine control to the "STOP" mode.

   3. Select "File/Select ECM" from the drop-down menu.

   4. Select the replacement ECM and click "OK".

   5. Select "Service/Copy Configuration/ECM Replacement" from the drop-down menu. Click "OK" on the window.

   6. Select "Program ECM" from the lower left corner of the screen. Select the replacement ECM and click "OK". If the correct ECM is shown, select "Yes".

   7. After the loading is complete, a window with the message "Programming Conflict Warning" will appear. Select "OK".

   8. A window with the message "Program ECM Results" will appear. Select "OK".

Note: When you program a new ECM, factory passwords are not required for the first hour of operation. After one hour, factory passwords are required for changing the parameters that are normally protected with factory passwords.

5. Calibrate the oxygen sensor and the speed/timing sensor.

   Refer to Troubleshooting, "Oxygen Sensor - Calibrate" and to Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".