AFTERCOOLER GP-AIR 3769731 - Caterpillar

This procedure is used for the following diagnostic codes:
248-09 Cat Data Link not communicating
248-12 Cat Data Link failedThe Cat Data Link is used for communication between electronic modules. The Cat Data Link is used to communicate information from the Electronic Control Module (ECM) to other electronic systems. The Cat Data Link is used for programming and troubleshooting the ECM.The ECM communicates with the Caterpillar Electronic Technician (ET) in order to share status information and diagnostic information. Cat ET can also be used to configure the ECM parameters. This information will not be available if communication fails between the ECM and Cat ET.
Illustration 1 g01252771
Typical modules on the Cat Data Link
Illustration 2 g01104274
P1 ECM connector
(P1-8) Cat Data Link +
(P1-9) Cat Data Link − Test Step 1. Inspect Electrical Connectors and Wiring
Turn OFF the power to the ECM.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the connectors to other modules on the Cat Data Link. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All of the connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Shorts in the Harness
Disconnect ECM connector J1/P1 at the engine ECM.
Disconnect all control modules from the Cat Data Link.
Disconnect Cat ET from the service tool connector J42.
Measure the resistance from P1-8 to every terminal on P1.
Measure the resistance from P1-8 to the chassis ground.
Measure the resistance from P1-9 to every terminal on P1.
Measure the resistance from P1-9 to the chassis ground. Expected Result:Each resistance measurement indicates an open circuit.Results:
OK - Each Measurement indicates an open circuit. Proceed to Test Step 3.
Not OK - At least one resistance measurement does not indicate an open circuit. There is a short circuit in the harness or connectors.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 3. Check for a Short in the Harness
Use a suitable piece of wire to create a short circuit at the cab service tool connector J42. Short J42-D and J42-E together.
Measure the resistance between P1-8 and P1-9.
Measure the resistance at the connectors of the other control modules. Expected Result:The resistance measurements indicate a short circuit.Results:
OK - Each resistance measurement indicates a short circuit. The Cat Data Link is OK.Repair: If the problem is intermittent,