78279 2 Mercury ELBOW FITTING, REED BLOCK (45 DEGREES)

Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
248-9 CAT Data Link not communicating     Communication with other control modules cannot be established within three seconds after the Electronic Control Module (ECM) is powered up. After communication with other control modules has been established, communication stops for one second.     The ECM will log the diagnostic code. All features that rely on the data link are disabled.    
248-12 CAT Data Link malfunction     Communication with other control modules cannot be established within three seconds after the ECM is powered up. After communication with other control modules has been established, communication stops for one second.     The ECM will log the diagnostic code. All features that rely on the data link are disabled.    
296-9 Transmission Control abnormal update rate     Communication with the transmission control cannot be established within three seconds after the ECM is powered up. After communication with the transmission control has been established, communication stops for one second.     The ECM will log the diagnostic code. All features of the transmission control that rely on the data link are disabled.    
296-12 See Service Manual         The ECM will log the diagnostic code.    Note: This procedure checks for an open circuit or for a short circuit in the Cat Data Link. If you are experiencing problems with communications between Caterpillar Electronic Technician (ET) and the ECM, refer to Troubleshooting, "Electronic Service Tool Does Not Communicate" before you use this procedure.The Cat Data Link is the standard data link that is used by the ECM to communicate with Cat ET. The ECM communicates with Cat ET in order to share status information and diagnostic information. Cat ET can also be used to configure the ECM parameters.
Illustration 1 g01415584
Typical schematic for the Cat Data Link
Illustration 2 g01394355
Service tool connector (Terminal D) Cat Data Link + (Terminal E) Cat Data Link −Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 3 g01167488
Engine view (typical example) (1) J1/P1 ECM connectors
Thoroughly inspect connector (1). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01415593
P1 terminals that are associated with the Cat Data Link (P1-8) Cat Data Link + (P1-9) Cat Data Link −
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the Cat Data Link.
Check the allen head screw on each ECM connector for the proper torque. Also, check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.Expected Result:All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and the connectors appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or the wiring are not OK.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. Verify that the original problem is resolved.STOPTest Step 2. Check for a Short Circuit
Disconnect the P1 ECM connector.
Disconnect Cat ET from the service tool connector.
Disconnect any other control modules from the Cat Data Link. Refer to the electrical schematic in order to identify other control modules on the Cat 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 Cat Data Link    
Connector and Terminal    Terminal    
P1-8 (Cat Data Link +)     All of the other terminals on the P1 connector    
Ground stud
P1-9 (Cat Data Link -)     All of the other terminals on the P1 connector    
Ground stud 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 3.
Not OK - At least one check of the resistance does not indicate an open circuit. There is a short circuit in the harness or in a connector.Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the original problem is resolved.STOPTest Step 3. Check for an Open Circuit
Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between terminals D (Cat Data Link +) and terminal E (Cat Data Link −) on the service tool connector.
Measure the resistance between P1-8 (Cat Data Link +) and P1-9 (Cat Data Link −).
Measure the resistance between the terminals at the connector for each control module that was connected to the Cat Data Link. Refer to Illustration 1.
Remove the jumper wire from the service tool connector.Expected Result:Each check of the resistance indicates a short circuit.Results:
OK - Each check of the resistance indicates a short circuit.Repair: Perform the following procedure:
Connect the J1/P1 connectors. Connect Cat ET to the service tool connector.
Check the Cat Data Link for proper operation. If the Cat Data Link does not operate correctly, there may be a problem with the ECM.Temporarily install a new ECM. Check the Cat Data Link again. If the new ECM solves the problem, install the original ECM and verify that the original problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "ECM - Replace".STOP
Not OK - At least one check of the resistance does not indicate a short circuit. There is an open circuit or excessive resistance in the harness. There may be a problem with a connector.Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Verify that the original problem is resolved.STOP