COVER AS 3727659 - Caterpillar

Illustration 1 g01368914
Schematic for the Cat Data Link
Illustration 2 g01360079
Connector location for the Cat Data Link (typical left side rear engine view) (1) Engine interface connector (70 pin) (2) Service tool connector (3) J1/P1 ECM connector
Illustration 3 g01312112
Terminal locations at the P1 ECM connector that are associated with the Cat Data Link (P1-8) Cat Data Link + (P1-9) Cat Data Link −
Illustration 4 g01367380
Terminal locations at the P1 ECM connector that are associated with the Cat Data Link (P1-8) Cat Data Link + (P1-9) Cat Data Link −
Illustration 5 g01365685
Terminal locations at the P1 ECM connector that are associated with the Cat Data Link (P1-8) Cat Data Link + (P1-9) Cat Data Link −
Table 1
Troubleshooting Test Steps     Expected Results     Results    
1. Inspect the Electrical Connectors and the Wiring
A. Remove electrical power from the ECM.
B. Thoroughly inspect connectors (1), (2), and (3). Refer to Troubleshooting, "Electrical Connectors - Inspect".
C. Perform a
45 N (10 lb) pull test on each of the wires that are associated with the Cat Data Link.
D. 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.    
All connectors, pins, and sockets are inserted and coupled completely. The harness and wiring are free of corrosion, of abrasion, and of pinch points.    
Result: The harness and the connectors appear to be OK. Proceed to Test Step 2
Result: The connectors and/or the wiring are not OK.
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 coupled completely. Verify that the original problem is resolved.    
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    
Negative ground
P1-9 (Cat Data Link -)     All of the other terminals on the P1 connector    
Negative ground
Table 3
Troubleshooting Test Steps     Expected Results     Results    
2. Check for a Short Circuit
A. Disconnect the P1 ECM connector.
B. Disconnect Cat ET from the service tool connector.
C. 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.    
Each check of the resistance indicates an open circuit.    
Result: Each check of the resistance indicates an open circuit. Proceed to Test Step 3.
Result: 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 the connectors and/or the wiring. Replace parts, if necessary. Verify that the original problem is resolved.    
3. Check for an Open Circuit
A. Fabricate a jumper wire that is long enough to create a test circuit across two terminals at the service tool connector. Use the jumper wire