CYLINDER GP-BRAKE 8I5209 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the Cat Data Link or if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
248-9 CAT Data Link abnormal frequency, pulse width, or period The Electronic Control Module (ECM) detects a loss of communication over the data link for two or more seconds. The code is logged. The Cat Data Link is used for communication between electronic modules. The data link is used to communicate information from the engine's Electronic Control Module (ECM) to Caterpillar Electronic Technician (ET). The data link is used for programming and troubleshooting the ECM.The ECM communicates with Cat ET in order to share engine information that may affect engine operation. The ECM communicates with the Cat ET in order to share status and diagnostic information. Cat ET can also be used to configure the ECM parameters on the engine. This information will not be available if communications fail between the ECM and Cat ET.
Illustration 1 g01199117
Typical example
Illustration 2 g01241456
P1 ECM connector
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
Illustration 3 g01241457
Customer connector
(Terminal h) Cat Data Link +
(Terminal g) Cat Data Link −
Illustration 4 g01241460
Service tool connector
(Terminal D) Cat Data Link +
(Terminal E) Cat Data Link −
Illustration 5 g01234146
Location of ECM connectors
Test Step 1. Inspect Electrical Connectors and Wiring
Turn the engine control switch (ECS) to the OFF/RESET position.
Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" 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 allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All 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 connectors and wiring are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring need repair.Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring.STOPTest Step 2. Check for Electrical Shorts in the Harness
Disconnect the ECM connectors.
Disconnect any module that is connected to the Cat Data Link.
Measure the resistance at the following points. Wiggle the harness during the measurement in order to reveal an intermittent short.
Cat Data Link + to Cat Data Link −
Cat Data Link + to −Battery terminal
Cat Data Link − to −Battery terminal
Cat Data Link + to +Battery terminal
Cat Data Link − to +Battery terminal
Cat Data Link + to engine ground
Cat Data Link − to engine groundExpected Result:The resistance is more than 20,000 Ohms for each measurement.Results:
OK - The resistance is greater than 20,000 Ohms. Proceed to Test Step 3.
Not OK - The resistance is less than 20,000 Ohms. There is a short in the harness or in the connectors.Repair: Repair