BOOM AS 3393949 - Caterpillar

Illustration 1 g01212749
The Electronic Control Module is located under the operator seat. (1) Transmission ECM (2) Connector "J2" (3) Connector "J1"Before the ECM is replaced, ensure that replacement is absolutely necessary. The ECM is seldom the cause of a diagnostic code. Always check that power is available to the ECM. Battery voltage is required from contacts 1 and 6 to contacts 2 and 5 of the machine harness connector "J1" for the ECM. Refer to "Check ECM voltage" for the procedure to check if the ECM needs to be replaced.Check ECM Voltage
Move the machine to a smooth horizontal location. Lower all implements to the ground. Engage the parking brake, and place chocks in front of the wheels and behind the wheels.
While the engine is running disconnect connector "J1" (3) . Contacts 1, 6 and 40 are common to each other and the contacts are used to provide system voltage to the ECM. Contacts 2 and 5 are common to each other and the contacts are used for machine ground. Measure the voltage between the power contacts 1, 6 and 40 to ground in order to check for power to the ECM.
If the voltage that is measured in Step 2 is 18 Volts DC to 32 Volts DC, the ECM voltage is acceptable for proper operation of the ECM. If the voltage that is measured is less than 18 Volts DC, there is a problem with the charging system. Refer to Special Instruction, "Charging System Troubleshooting" for information on troubleshooting the charging system. If no voltage was measured in Step 2, proceed to Step 4.
Check the fuse for the Transmission ECM. If the fuse is good, check the 126-PK wires in the machine harness for an open circuit, or for a poor connection. If a problem is found, repair the harness or replace the harness.
If the ECM must be replaced then proceed to "Removal Procedure".Removal Procedure
Turn the disconnect switch and the key start switch to the OFF. Disconnect the harness from the ECM.
Remove the bolts that secure the ECM to the machine.
Remove the ECM.
Install the replacement ECM.
Connect the harness to the replacement ECM and tighten screw (3) .
If the ECM is not programmed, flash new software to the ECM. For more information on flashing new software, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Flash Program" for the machine that is being serviced.
Perform the necessary calibrations. For information on performing calibrations, refer to Testing and Adjusting, "Calibration".
Check for any active diagnostic codes after you replace the implement ECM.ReferenceFor more information about clearing diagnostic codes, refer to Troubleshooting, "Using the Caterpillar Electronic Technician to Determine Diagnostic Codes".