0584824 JOHNSON SENSOR ASSY.

Table 1
Diagnostic Codes Table    
Description     Conditions which Generate this Code     System Response    
247-9 SAE J1939 Data Link abnormal update rate     The Electronic Control Module (ECM) detects a loss of communication over the data link for two or more seconds or the ECM detects an incorrect transmission.     The warning lamp will illuminate, if equipped.
The code is active.
The code is logged.    
247-12 SAE J1939 Data Link failure     The ECM detects a loss of communication over the data link for two or more seconds or the ECM detects an incorrect transmission.     The warning lamp will illuminate, if equipped.
The code is active.
The code is logged.    The CAN data link is also known as J1939 Data Link. The data link is for sending data between different devices in the same application.High speed data is transfered via the data link. The data link requires a resistance of 60 Ohms between the two wires to correctly transmit the data. This resistance is made up of two 120 Ohm terminating resistors at opposite ends of a data link network. If this resistance is not present, then the data will be intermittent or completely unreadable.Note: If the wiring is damaged the replacement type must be shielded twisted pair cable.
Illustration 1 g01325043
Typical schematic for the CAN data link
Illustration 2 g01325042
A typical view of the P1 connector (harness side) pin locations. (21) CAN- (20) CAN+ (22) CAN shield
Illustration 3 g01325045
A typical example of the P2 connector (harness side) pin locations. (23) CAN- (24) CAN+ (22) CAN shieldTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the connectors to other modules on the CAN data link. Refer to service Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the CAN data link.
Check the allen head screw on each ECM connector for the proper torque. Refer to service Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the wiring harnesses for abrasion, for corrosion and for pinch points.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the wiring harness.Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.If applicable, perform the "Wiggle Test" on Caterpillar Electronic Technician (ET).Use Cat ET in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.STOPTest Step 2. Verify the Proper Installation of the CAN Data Link
Disconnect all modules that are connected to the CAN data link.
Disconnect the P1 connector and the P2 connector. Measure the resistance between terminals P1-20 (CAN data link +) and P1-21 (CAN data link -).
Measure the resistance between terminals P2-24 (CAN data link +) and P2-23 (CAN data link -).Expected Result:The resistance is between 54 and 66 Ohms.Results:
OK - The resistance is between 54 and 66 Ohms.Repair: If the CAN data link is working properly at this time, there may be an intermittent problem. If the problem is intermittent, refer to service Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The resistance is between 108 and 132 Ohms. The terminating resistor is missing.Repair: Verify that two terminating resistors exist on the data link. One resistor must be located on each end of the data link. The engine is shipped with one terminating resistor that is installed between the ECM and the customer connector.Refer to the appropriate electrical schematic in order to determine the missing resistor. Replace the missing resistor.Use Cat ET in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.STOP
Not OK - The resistance is less than 54 Ohms. Proceed to Test Step 3.
Not OK - The resistance is greater than 132 Ohms. Proceed to Test Step 4.Test Step 3. Check for a Short Circuit
Remove the terminating resistors from the CAN data link.
Measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Table 2
Resistance Measurements for the CAN Data Link    
Connector and Terminal    Terminal    
P1-20 (CAN data link +)     All of the other terminals on the P1 connector    
Engine ground
P1-21 (CAN data link -)     All of the other terminals on the P1 connector    
Engine ground
P2-24 (CAN data link +)     All of the other terminals on the P2 connector    
Engine ground
P2-23 (CAN data link -)     All of the other terminals on the P2 connector    
Engine ground Expected Result:Each check of the resistance indicates an open circuit.Results:
OK - Each check of the resistance indicates an open circuit. Proceed to Test Step 4.
Not OK - At least one check of the resistance does not indicate an open circuit. There is a short circuit in a harness. There may be a problem with a connector.Repair: Repair the wiring and/or the connector.Use Cat ET in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.STOPTest Step 4. Check for an Open Circuit
Verify that all of the connections are disconnected.
Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between terminals G and F on the service tool connector.
Measure the resistance between terminals P1-20 (CAN data link +) and P1-21 (CAN data link -).
Measure the resistance between terminals P2-24 (CAN data link +) and P2-23 (CAN data link -).
Measure the resistance between the terminals at the connector for each control module that was connected to the CAN data link.
Remove the jumper wire from the service tool connector.Expected Result:The resistance is