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CAT Data Link connections | |
The MID 081, CID 0248 diagnostic code is associated with the Cat Data Link communication circuits. The Cat Data Link system is used to communicate machine system status information to other controls modules on the machine. The data link is used to communicate with the Caterpillar Electronic Technician service tool.
The FMI 09 means that the Transmission ECM is not receiving any communication from the other control modules that are connected on the Cat Data Link communication circuits.
The possible conditions that can cause the Transmission ECM to activate this communication diagnostic code against each ECM on Cat Data link are listed.
- An open circuit or a poor connection of any other ECM to the Cat Data link.
- When any ECM on Cat Data link failed.
- Any of the ECMs on Cat data link powered up after some specified time of the Transmission ECM powering up or any other ECM powering downed before some specified time of Transmission ECM power down
- When the Transmission ECM failed to receive any of the expected messages from any of the ECMs on Cat Data link
Proceed with the following procedure to isolate the cause of the problem.
Test Step 1. CHECK THE DATA LINK CIRCUIT FOR AN OPEN
- Turn the key switch and the battery disconnect switch to the OFF position.
- At the Transmission ECM, disconnect the J1 harness connector. Check the condition of the harness connector contacts and the ECM connector contacts. Ensure that all the pins and sockets are secured in the connector, the contacts are clean, and the contacts are in good condition.
- At the harness connector J1, connect a jumper wire between the data link contacts J1-10 (wire 893-GN) and J1-20 (wire 892-BR).
- At the data link service connector in the cab, measure the resistance of the system between the data link positive contact D (wire 893-GN) and contact E (wire 892-BR).
Expected Result:
The resistance measurement is less than 5 ohms.
Results:
- OK - The resistance measurement is less than 5 ohms. The Cat Data Link circuits between the Transmission ECM and the service connector are not open. Before proceeding to the next step, disconnect the jumper wire that is connected to the ECM harness connector contacts. Proceed to Test Step 2.
- NOT OK - The resistance measurement is greater than 5 ohms. There is an open circuit or a poor connection in the Cat Data Link circuits between the Transmission ECM and the service connector.
Repair: The open circuit is most likely in the Transmission ECM harness connector or in a connector that is close to the ECM.
The connection diagram at the beginning of this procedure shows the end connections for the data link circuits. Refer to the complete machine electrical schematic that is in the Service Manual for all the harness connections in the data link circuits.
Locate and examine all the circuit connections that are used in the suspected sections of the data link circuit. Check each wire section from connector to connector for an open or a bad connection. Ensure that all connections are clean, secure, and in good condition.
Find the open circuit or poor connection in the data link circuits to resolve this problem.
STOP
Test Step 2. CHECK THE DATA LINK CIRCUIT FOR A SHORT
The key switch and the battery disconnect switch remain in the OFF position.
The Transmission ECM J1 harness connector remains disconnected from the ECM.
The jumper wire that was used in the last test step is no longer connected.
- At the Transmission ECM, disconnect the J2 harness connector. Check the condition of the harness connector contacts and the ECM connector contacts. Ensure that all the pins and sockets are secured in the connector, the contacts are clean, and the contacts are in good condition.
- At the Transmission ECM J1 harness connector, measure the resistance between the Cat Data Link positive contact J1-10 (893-GN(Green)) and a good cab ground point. Measure the resistance between the data link positive contact J1-10 and all the other circuit contacts that are used on the Transmission ECM J1 and J2 harness connector contacts.
- At the Transmission ECM J1 harness connector, measure the resistance between the Cat Data Link negative contact J1-20 (892-BR(Brown)) and a good cab ground point. Measure the resistance between the data link negative contact J1-20 and all the other circuit contacts that are used on the Transmission ECM J1 and J2 harness connector contacts.
Expected Result:
Each individual resistance measurement between the Cat Data Link contacts, frame ground, and the other Transmission ECM circuits is greater than 4000 ohms.
Results:
- OK - The Cat Data Link circuits do not appear to be shorted to frame ground or to any other circuit in the Transmission ECM harness. Proceed to Test Step 3.
- NOT OK - One or more of the resistancemeasurementis less than 4000 ohms. There is a short circuit between the Cat Data Link circuits and either frame ground or another circuit in the machine harness.
Repair: Locate and examine all the circuit connections that are used in the suspected sections of the Cat Data Link circuits. Start at the Transmission ECM and check each wire section from connector to connector for conditions that could cause a short circuit. Ensure that all connections are clean, secure, and in good condition. Look for areas where the harness could be in contact with the frame resulting in a short circuit.
Find the short circuit in the data link circuits to resolve this problem.
STOP
Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Reconnect all the disconnected machine harness connectors. Make sure that the connectors are fully seated and locked or make sure that the retaining bolts are tight.
- Turn the battery disconnect switch and the key start switch to the ON position. Do not start the engine.
- Check the status of the MID 081, CID 0248 FMI 09 diagnostic code.
Expected Result:
The MID 081, CID 0248 FMI 09 diagnostic code is not active.
Results:
- OK - The MID 081, CID 0248 FMI 09 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or contamination at one of the connectors that was disconnected and reconnected.
STOP
- NOT OK - The MID 081, CID 0248 FMI 09 diagnostic code is still active. The problem that is causing the Transmission ECM to activate the diagnostic code has not been corrected.
Repair: Perform this procedure again. Verify again that there is no problem with the machine harness or the wiring connections.
If the diagnostic code is still active and no cause can be found, flash latest version of software to the Transmission ECM.
NOTE: When flashing software to the Transmission ECM, the ECM will be listed in “WinFlash” as the “Transmission ECM”. Select the Transmission ECM to flash software to the Transmission ECM. All other applications will refer to the ECM as the Transmission ECM.
If the diagnostic code is still being activated only by the Transmission ECM, contact your dealerships technical communicator for possible consultation with Caterpillar.
If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP