866784T01 Mercruiser HARNESS ASSEMBLY, Extension

Illustration 1 g01162523
Schematic diagram of the Cat Data LinkTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01144470
Left side engine view (typical example)
Thoroughly inspect connector (1). Also, thoroughly inspect the connectors for each of the machine's control modules that are associated with the Cat Data Link. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01104274
P1 terminals for the Cat Data Link (engine ECM) (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 torque of the allen head screws for each of the ECM connectors. 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
Verify that the keyswitch is in the OFF position.
Disconnect Cat ET from the service tool connector.
Measure the resistance between the points that are listed in Table 1. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Table 1
Service Tool Connector
Resistance Measurements for the Cat Data Link    
Terminal    Terminal    
D (Cat Data Link +)     E (Cat Data Link -)    
A (+Battery)
B (-Battery)
E (Cat Data Link -)     A (+Battery)    
    B (-Battery)    Expected Result:Each check of the resistance indicates an open circuit.Results:
OK - Each check of the resistanceindicates 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 a harness. There may be a problem 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 in the Data Link Harness
Fabricate a jumper wire that is long enough to create a short circuit in the wires at the service tool connector. Crimp connector sockets to each end of the jumper wire. Install the jumper wires between terminals D (Cat Data Link +) and E (Cat Data Link −) at the service tool connector.
Disconnect the appropriate connector from the suspect machine control module.
Measure the resistance between the terminals for the Cat Data Link on the connector for the suspect module. Be sure to wiggle the wires in the harnesses as you measure the resistance.Expected Result:The resistance measurement indicates a short circuit between the terminals for the data link.Results:
OK - The resistance measurement indicates that a short circuit exists. The wiring between the service tool connector and the connector for the suspect machine control module does not have an open circuit. Proceed to Test Step 4.
Not OK - The resistance measurement 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.STOPTest Step 4. Check the Machine Control ModulesTemporarily install a new module in place of the suspect module. Check for the diagnostic code again.Expected Result:The diagnostic code is not active when the suspect module is replaced.Results:
OK - The diagnostic code is not active when the suspect module is replaced.Repair: If the problem is resolved with a new module, install the original module and verify that the problem returns. If the new module works correctly and the original module does not work correctly, replace the original module.STOP
Not OK - The diagnostic code remains active when the suspect machine control module is replaced.Repair: Install the original module. Then, temporarily install one of the other machine control modules that is associated with the Cat Data Link. After you temporarily install each module, check for the code again. When the diagnostic code is no longer active, the faulty module has been identified. Replace the faulty module.STOP