19941 55 Mercury SCREW, (M5 x 55)

Table 1
Diagnostic Trouble Codes
CDL Code Code Description Comments
246-9 Proprietary CAN Data Link : Abnormal Update Rate The Electronic Control Module (ECM) has lost communications over the CAN data link.
The code is logged.
247-9 SAE J1939 Data Link : Abnormal Update Rate The ECM has lost all communications over the global CAN data link.
The code is logged.
596-9 Implement Control : Abnormal Update Rate The ECM has lost all communications with the implement control over the Cat Data Link.
The code is logged.
1603-9 Machine Control Module : Abnormal Update Rate The code is logged.
3243-9 Water Pump Control Module : Abnormal Update Rate The ECM has lost all communications with the water pump control module.
The code is logged. If the Caterpillar Electronic Technician (ET) will not communicate with the ECM, refer to Troubleshooting, "Electronic Service Tool Does Not Communicate" before you begin this procedure. The procedure verifies that electrical power is being supplied to the ECM and to the service tool connector.The data links are used to communicate information between the engine ECM and other control modules that are a part of the application. Cat ET also communicates with the ECM via the data links.The service tool connector contains connections for electrical power and for the data links.When the keyswitch is in the OFF position, Cat ET may communicate with the ECM. However, the communications may be disrupted and the communications may require frequent reconnection. In order to avoid this problem, place the keyswitch in the ON position when Cat ET is being used.Cat ET may display the following error message:"The version of the ECM is not recognized and the integrity of the changed parameters and displayed data is not guaranteed."This message indicates that one of the following conditions exist:
The flash file in the ECM is newer than the version of Cat ET.
The latest version of Cat ET has not been installed.
Illustration 1 g02112358
Schematic for the Cat Data Link and the CAN data link
Illustration 2 g01672679
Terminal locations at the service tool connector
(A) +Battery
(B) −Battery
(C) CAN shield
(D) Cat Data Link +
(E) Cat Data Link −
(F) CAN data link −
(G) CAN data link +
Illustration 3 g01672676
Terminal locations at the P1 ECM connector that are for the data link
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
(P1-34) CAN data link −
(P1-42) CAN shield
(P1-48) +Battery (if applicable)
(P1-50) CAN data link +
(P1-52) +Battery (if applicable)
(P1-53) +Battery (if applicable)
(P1-61) −Battery (if applicable)
(P1-63) −Battery (if applicable)
(P1-65) −Battery (if applicable)
(P1-70) Keyswitch
Illustration 4 g02078636
P2 ECM connector
(P2-11) CAN data link −
(P2-12) CAN data link +
Table 2
Troubleshooting Test Steps Values Results
1. Check for a Short Circuit
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect the connectors that are associated with the data link circuits. Refer to Troubleshooting, "Electrical Connectors - Inspect".
C. Disconnect the P1 and the P2 ECM connector.
D. Disconnect Cat ET from the service tool connector.
E. Measure the resistance between the points that are listed in Table 3. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Short circuit
Results: Each check of the resistance indicates a short circuit. - Remove the jumper wire from the service tool connector. Proceed to Test Step 3.
Results: At least one of the resistance measurements indicates an open circuit.
Repair: Remove the jumper wire from the ECM connector. Determine the cause of the open circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the problem is resolved.
STOP
2. Check for an Open Circuit
A. Fabricate a jumper wire that is long enough to create a test circuit across two terminals. Create a short circuit between terminals G (CAN data link +) and F (CAN data link −) on the service tool connector.
B. Measure the resistance between P1-50 (CAN data link +) and P1-34 (CAN data link +).
C. Fabricate a jumper wire that is long enough to create a test circuit across two terminals. Use the jumper wire in order to create a short circuit between terminals 23 (CAN data link +) and 24 (CAN data link −) on the Clean Emissions Module (CEM) connector.
D. Measure the resistance between P2-12 (CAN data link +) and P2-11 (CAN data link −).
Open circuit
Results: Each check of the resistance indicates a short circuit. - Remove the jumper wire from the service tool connector. Proceed to Test Step 3.
Results: At least one of the resistance measurements indicates an open circuit.
Repair: Remove the jumper wire from the ECM connector. Determine the cause of the open circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the problem is resolved.
STOP
Table 3
Resistance Measurements for the Data Link
Connector and Terminal Terminal
P1-8 (Cat Data Link +) All of the other terminals on the P1 connector
Negative ground
P1-9 (Cat Data Link -) All of the other terminals on the P1 connector
Negative ground
P1-50 (CAN data link +) All of the other terminals on the P1 connect