SENSOR GP-SPEED 2932878 - Caterpillar

This procedure is used for the following diagnostic codes:
248-09 Cat Data Link not communicating
248-12 Cat Data Link failed
296-09 Unable to communicate with Transmission ECM
296-12 See Service Manual
562-09 Unable to Communicate with Cat Monitoring System
562-12 Wrong Response from Cat Monitoring SystemThe Cat Data Link provides data communication line between the different control modules that are on the machine. The Cat Data Link is used to communicate information from the engine's Electronic Control Module (ECM) to the other electronic systems. The Cat Data Link is also used for communication between the control modules and Caterpillar Electronic Technician (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. This information will not be available if communication fails across the Cat Data Link.The ECM sends information to the electronic dash displays in order to communicate the engine's operating status to the operator of the machine. The ECM also communicates with other machine control modules in order to perform machine functions. The following modules are available for this application. These modules communicate over the Cat Data Link:
Engine ECM
Implement ECM
Power train ECM
Advisor
Driver information display
Machine Security System (MSS)
Illustration 1 g01249777
Schematic for the Cat Data Link (typical example)
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the engine ECM.
Illustration 2 g01214624
J1/P1 ECM connectors (typical left side engine view)
Thoroughly inspect the J1/P1 ECM connectors. Inspect all of the connectors to other modules that are on the Cat Data Link. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01207225
Terminals at the P1 ECM connector for 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 in the ECM connector that are associated with the circuit.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
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 the J1/P1 ECM connectors.
Disconnect all control modules from the Cat Data Link.
Disconnect Cat ET from the service tool connector . Note: Wiggle the harness during the following measurements in order to reveal an intermittent condition.
Measure the resistance from P1-8 to every terminal on the P1 ECM connector.
Measure the resistance from P1-8 to the chassis ground.
Measure the resistance