SHIELD AS 3511081 - Caterpillar

Illustration 1 g01114123A circuit breaker is opened as a result of an overloaded circuit. For example, the +battery connection is shorted to ground. If the circuit breaker is open on a supply circuit for the ECM, no diagnostic code will be recorded. A circuit breaker open does not result in a recorded service code in the Propel ECM, it will cause the service code CID 248 FMI F11 to be logged by the Conveyor ECM.Whenever the machine's electronic components fail to function and no diagnostic code is active, check the circuit breaker for that component and check all other associated circuit breakers. Repeated circuit breaker openings will indicate a problem with a circuit component or the machine wiring harness.When the key switch is turned to the ON position, The main power relay (MPR) contacts should close which will allow +battery power to reach the ECM through the propel circuit breaker (CB 3). If the key switch is in the ON position and no activity is observed on the ECM three digit display, perform the following procedure.Note: The main disconnect switch should be in the ON position.Test Step 1. Check Circuit BreakersThe key switch is OFF.
Check for an open at the propel circuit breaker (CB 3).
Check for an open at the main circuit breaker (CB 1). Expected Result:Either the propel circuit breaker or the main circuit breaker is open.Results:
YES - A circuit breaker is open.Repair: Reset the open circuit breaker. Resume machine operation.STOP
NO - CB 1 or CB 3 are not open. Proceed to Test Step 2.Test Step 2. Check ECM Power SupplyThe key switch is OFF.
Disconnect the machine harness from the ECM.
Turn the key switch to the ON position.
Using a multimeter, measure the DC voltage from the machine harness connector contact 1 (+ battery) to contact 39 (- battery). Expected Result:The voltage measurement shows little or no DC voltage.Results:
YES - The voltage measurement shows little or no DC voltage. Proceed to Test Step 3.
NO - The voltage measurement shows that between 23 VDC and 32 VDC is present at ECM contact 1.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Refer to the Electrical System Schematic for this machine and check all involved wiring harness connectors and wiring. Ensure that the ECM connector contacts are clean and in good condition. Ensure that all machine harness wiring is intact and in good condition. If the ECM fails to energize after this procedure has been performed, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) − Replace" in this manual.STOPTest Step 3. Check Power Supply CircuitThe key switch remains ON. The ECM harness connector remains disconnected.
At the propel circuit breaker (CB 3), measure the DCV from the supply side contact (wire P112-PU(Purple)) to ECM harness connector contact 2 (- Battery). Expected Result:The voltage measurement shows that between 23 VDC and 32 VDC is present at the supply