BLOCK 1748789 - Caterpillar

System Operation Description:Power to the ECM can fail due to an open circuit in the wire, or a blown fuse. A fuse is blown out as a result of an overloaded circuit. For example, the +battery connection is shorted to ground.Test Step 1. CHECK THE ECM FOR POWER AND GROUND.At the ECM, measure the voltage from contact 1 to contact 2. Expected Result:The voltage is system voltage.Results:
OK - The voltage is system voltage. The power supply circuit to the ECM is correct. STOP
NOT OK - The voltage is not system voltage. Proceed to Test Step 2.Test Step 2. CHECK THE FUSEWhenever the machine's electronic components fail to function, check the appropriate fuse for the ECM.
Check the fuse for the ECM.Expected Result:The fuse is correct.Results:
YES - The fuse is correct. Proceed to Test Step 3.
NO - The fuse is not correct.Repair: Replace the blown fuse or reset the circuit breaker. Observe the machine for a recurrence of the problem. If the problem persists, the reason for the blown fuse must be isolated and corrected.STOPTest Step 3. CHECK THE POWER WIRE TO THE ECM.
Turn the key start switch and the disconnect switch to the OFF position.
At the fuse, connect the lead from the multimeter to wire 113-RD.
At the ECM, connect the other lead from the multimeter to connector contact 1 and measure the resistance.Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. The wiring circuit is correct. Proceed to Test Step 4.
NOT OK - The resistance measurement is greater than 5000 ohms. The wiring has an open circuit.Repair: Repair the wiring harness or replace the wiring harness. STOPTest Step 4. CHECK THE ECM GROUND CONNECTIONS.
The keyswitch and the disconnect switch remain in the OFF position.
At the ECM, measure the resistance from connector contact 2 to frame ground.Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. The ground circuit is correct. The ECM may have failed. This is unlikely. Perform this entire procedure again. If the problem remains, the ECM may need to be replaced. Contact your dealerships for possible consultation with Caterpillar. This consultation may greatly reduce repair time.STOP
NOT OK - The resistance is greater than 5000 ohms. The ground circuit has failed.Repair: The ground circuit has failed. Repair the wiring harness or replace the wiring harness.STOP