0326784 JOHNSON WASHER, Screw, long

Table 1
Event Code
J1939 Code and Description Conditions which Generate this Code System Response
561-31
Backup ECM Took Control The secondary ECM detected that the primary ECM is having difficulties controlling the engine. The code is logged.
The secondary assumes control of the engine. Probable Causes
Battery voltage to the primary ECM
Loss of primary ECM heartbeat message
Diagnostic codes for the injector solenoids
Engine overspeedThe primary ECM periodically broadcasts a message over the CAN data link and CDL Data Links that communicates the condition of the primary ECM. This message is recognized by the secondary ECM as the ECM heartbeat status of the primary ECM. If the heartbeat message is lost or unreadable, the secondary ECM will assume control of the engine.The secondary ECM continuously transmits a ready status message over the CAN data link and CDL Data Links. As long as the secondary ECM is broadcasting a status of "Ready", the secondary ECM is eligible to take control of the engine.Note: The power to the engine must be cycled prior to allowing the primary ECM to resume control of the engine.Recommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.Recommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
C. Determine if the diagnostic trouble code that directed to this procedure is present.
D. Look for active diagnostic codes that are associated with the system for the event code that directed to this procedure.
561-31
Result: An associated code is present.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A 561-31 code is present.
Proceed to the next step.
Result: No active codes
STOP
2. Check the Battery Voltage to the Primary ECM
A. Connect Caterpillar Electronic Technician (ET). Establish communication with the primary ECM.
B. If communication with the primary ECM cannot be established, verify that voltage is present at the primary ECM. If voltage is not present at the keyswitch input or battery voltage at the primary ECM, refer to Troubleshooting, "Electrical Power Supply - Test".
Voltage
Result: The voltage check is OK.
Proceed to the next step.
Result: The voltage check is NOT OK.
Repair: Repair the low voltage condition.
If the problem is not resolved, proceed to the next step.
3. Check the Loss of Primary ECM Heartbeat Message
A. The secondary ECM will assume control of the engine if the primary ECM heartbeat signal to the secondary ECM is interrupted.
B. The secondary ECM will remain in control of governing until keyswitch power to the primary ECM has been cycled.
Heartbeat
Result: The primary ECM is OK.
Proceed to the next step.
Result: The primary ECM is NOT OK.
Repair: Repair or replace the faulty ECM.
If the problem is not resolved, proceed to the next step.
4. Check for Multiple Diagnostic Codes for the Injector Solenoids
A. If multiple diagnostic codes for the injector solenoids are active at the same time, then the primary ECM will terminate. The secondary ECM will assume control of governing if the primary ECM heartbeat signal to the secondary ECM is interrupted.
B. Check for active diagnostic codes or for logged diagnostic codes for the injector solenoids.
Codes
Result: Injector codes are not present.
Proceed to the next step.
Result: Injector codes are present.
Repair: Refer to Troubleshooting, "Injector Solenoid - Test".
If the problem is not resolved, proceed to the next step.
5. Check for Engine Overspeed Condition
A. If an engine overspeed occurs, the secondary ECM will assume control of governing.
B. 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.
Overspeed
Result: There is no overspeed condition.
Proceed to the next step.
Result: There is an overspeed condition.
Repair: Determine the cause for the engine overspeed. Refer to Troubleshooting, "Engine Overspeeds"
If the problem is not resolved, proceed to the next step.