CLIP 0005401 - Caterpillar

Electronic Control Module (ECM) - Replace
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 between contacts J1-1 and J1-2 of the machine harness connector for the ECM. Continue ONLY if all other attempts to isolate the problem have failed. Always consult your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce the time that is required for a repair.
Turn the disconnect switch and the key start switch to the OFF position. Disconnect the machine harness from the ECM.
Remove the ECM.
Make sure that the replacement ECM is the correct part number.
Connect the machine harness to the ECM.
Install the replacement ECM.