C18 Generator Set Engines Caterpillar

Use this procedure in order to troubleshoot the reason that the secondary Electronic Control Module (ECM) has assumed control of the engine. Use this procedure to troubleshoot the following event code:

• E048(1) Backup ECM Took Control

Probable Causes

• The heartbeat signal from the primary ECM is lost.

• There is more than one diagnostic code for the injector solenoids.

• Engine overspeed

Recommended Actions

Battery Voltage to the Primary ECM

An interruption in the electrical power to the primary ECM can cause the loss of the heartbeat signal.

Connect Caterpillar Electronic Technician (ET). Establish communication with the primary ECM. If communication with the primary ECM cannot be established, verify that voltage is present at the primary ECM. Refer to Troubleshooting, "Electrical Power Supply - Test".

Loss of Primary ECM Heartbeat Signal

Verify that the wire that carries the primary ECM heartbeat signal to the secondary ECM is OK. The secondary ECM will remain in control of governing until keyswitch power to the primary ECM has been cycled.

Multiple Diagnostic Codes for the Injector Solenoids

If two or more diagnostic codes for the injector solenoids are active, the primary ECM will terminate the heartbeat signal to the secondary ECM. The secondary ECM will assume control of governing. Check for active diagnostic codes or for logged diagnostic codes for the injector solenoids. If multiple diagnostic codes for the injectors are active or logged, refer to Troubleshooting, "Injector Solenoid - Test".

Engine Overspeed

If an engine overspeed occurs, the secondary ECM will assume control of governing. The secondary ECM will stop fuel injection to the engine. The secondary ECM will remain in control of governing until keyswitch power to the primary ECM has been cycled. Determine the cause for the engine overspeed. Refer to Troubleshooting, "Engine Overspeeds".