872383 Volvo.Penta Diode bridge

Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
248-9 Cat Data Link Long not communicating     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 g01248449
Typical schematic
Illustration 2 g01241456
P1 ECM connector (P1-8) Cat Data Link + (P1-9) Cat Data Link −
Illustration 3 g01241460
Service tool connector (Terminal D) Cat Data Link + (Terminal E) Cat Data Link −
Illustration 4 g01234146
Location of ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the local/remote switch on the control panel 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 indicates an open circuit for each measurement.Results:
OK - The resistance indicates an open circuit for each measurement. Proceed to Test Step 3.
Not OK - The resistance does not indicate an open circuit. There is a short in the harness or in the connectors.Repair: Repair the connector and/or wiring or replace the connector and/or wiring.STOPTest Step 3. Check the Resistance through the Harness for an Open Circuit
Short the wires of the Cat Data Link together. Create the short at P1-9 and P1-8 of the ECM connector.
Set an ohmmeter on the 200 Ohm scale. Measure the resistance between the terminals of the Cat Data Link + and the Cat Data Link −. Measure the resistance at the connectors for the ECM. Measure the resistance between the terminals of any module that was connected to the Cat Data Link. Wiggle the harness during the measurements in order to reveal an intermittent open condition.
Reconnect all connectors and modules.Expected Result:The resistance indicates a short circuit for each measurement.Results:
OK - The resistance indicates a short circuit for each measurement.Repair: The harness is OK. There could be a problem with a module or with the ECM. Connect the suspect module on another engine. If the problem returns on the other engine, replace the suspect module. Turn the keyswitch to the OFF position. Turn the keyswitch to the STOP position. If the diagnostic code is still present, replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".STOP
Not OK - The resistance does not indicate a short circuit for each measurement.Repair: There is an open circuit or there is excessive resistance in the harness. Repair the connectors and/or wiring or replace the connectors and/or wiring.STOP