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| Illustration 1 | g01251041 |
Schematic of the Primary and Secondary Keypad Shifters | |
This diagnostic trouble code is recorded when the Transmission ECU does not receive expected information from the gear shifter for a period of more than five seconds.
Test Step 1. VERIFY THE HARDWARE AND THE SOFTWARE PART NUMBERS.
- Verify that the following information is correct:
- The part number of the flash software for the Transmission ECU
- The part number of the flash software for the gear selector
- The part number of the Transmission ECU
- The part number of the gear selector
Note: Consult your Caterpillar Dealer for the correct part numbers of the flash software.
- The part number of the flash software for the Transmission ECU
Expected Result:
All of the part numbers are correct.
Results:
- OK - All of the part numbers are correct. Proceed to Test Step 2.
- NOT OK - All of the part numbers are not correct.
Repair: The installed Transmission ECU or the gear selector have the wrong part number or the incorrect flash software is installed. Replace the incorrect Transmission ECU or the gear selector with a module that has the correct part number. Flash the correct software. See the Testing and Adjusting, "Electronic Control Unit - Flash Program" section for additional information.
STOP
Test Step 2. INSPECT THE HARNESS CONNECTIONS.
- Turn the disconnect switch to the OFF position.
- Inspect all harness connections that are related to the CAN Data Link. Make sure that the connectors are clean and tight.
- Check the connectors for proper mating. Ensure that all the seals are present and in place.
- Check the harness for signs of damage or abrasion.
- Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector.
- Check the exposed wires at the connectors for nicks or signs of abrasion.
- Check for moisture inside the connector.
- Check the connectors for dirty contacts or corroded contacts.
- Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.
Expected Result:
The machine harness connectors are tight and free of corrosion.
Results:
- OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 3.
- NOT OK - The machine harness connectors are in need of repair.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK FOR SHORTS TO GROUND
- The disconnect switch remains in the OFF position.
- Disconnect the machine harness connectors from all electronic control modules that use the CAN Data Link.
- At the machine harness for the Transmission ECU, measure the resistance between frame ground and connector contacts J2-67 (wire K900-YL) and J2-68 (wire K990-GN) of the CAN Data Link circuit.
Expected Result:
The resistance is greater than 5000 ohms.
Results:
- OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Test Step 4.
- NOT OK - The resistance is less than 5000 ohms. The machine harness has failed.
Repair: There is a short between frame ground and contacts J2-67 (wire K900-YL) and J2-68 (wire K990-GN) of the CAN Data Link circuit in the machine harness. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK FOR SHORT TO THE +BATTERY CIRCUIT
- The disconnect switch remains in the OFF position.
- All related electronic control modules remain disconnected from the machine harness.
- At the machine harness connector for the Transmission ECU, perform the checks that are listed here:
- Measure the resistance between the connector contact J1-47 (wire 126-PK) and connector contact J2-67 (wire K900-YL).
- Measure the resistance between connector contact J1-47 (wire 126-PK) and connector contact J2-68 (wire K990-GN).
- Measure the resistance between the connector contact J1-47 (wire 126-PK) and connector contact J2-67 (wire K900-YL).
Expected Result:
The resistance is greater than 5000 ohms.
Results:
- OK - The harness circuit resistance is correct. Proceed to Test Step 5.
- NOT OK - The resistance is less than 5000 ohms. The machine harness has failed.
Repair: There is a short between the +battery circuit and contacts J2-67 (wire K900-YL) and J2-68 (wire K990-GN) of the CAN Data Link circuit in the machine harness. Repair the machine harness or replace the machine harness.
STOP
Test Step 5. CHECK FOR OPEN HARNESS
- The disconnect switch remains in the OFF position.
- All related electronic control modules remain disconnected from the machine harness.
- Check the resistance of the CAN Data Link circuit in the machine harness:
- Measure the resistance between connector contact J2-67 (wire K900-YL) of the Transmission ECU and connector contact 1 (wire K900-YL) of the gear selector.
- Measure the resistance between connector contact J2-68 (wire K990-GN) of the Transmission ECU and connector contact 7 (wire K990-GN) of the gear selector.
- Measure the resistance between connector contact J2-67 (wire K900-YL) of the Transmission ECU and connector contact 1 (wire K900-YL) of the gear selector.
Expected Result:
The resistance measures less than 5 ohms.
Results:
- OK - The resistance is less than 5 ohms. The CAN Data Link circuit in the machine harness is correct. Proceed to Test Step 6.
- NOT OK - The resistance is greater than 5 ohms. The machine harness has failed.
Repair: The CAN Data Link circuit is open in the machine harness. Repair the machine harness or replace the machine harness.
STOP
Test Step 6. CHECK FOR ADDITIONAL DIAGNOSTIC TROUBLE CODES FOR THE GEAR SHIFTER AND FOR OTHER ELECTRONIC CONTROL MODULES.
- Turn the key start switch and the disconnect switch to the OFF position.
- One at a time, reconnect the electronic control modules that use the CAN Data Link.
- Turn the disconnect switch and the key start switch to the ON position.
- After each of the electronic control modules has been reconnected, check for diagnostic trouble codes that are logged against that electronic control unit.
Expected Result:
Diagnostic trouble codes are not present for the other electronic control units.
Results:
- OK - Diagnostic trouble codes are not present for the other electronic control units. The gear selector has failed.
Repair: Check the circuit again. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a "Wiggle Test" on the Transmission wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the Transmission wiring harness. It is unlikely that the ECU has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic trouble code is not found, replace the ECU. Prior to replacing an ECU, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Unit - Replace".
STOP
- NOT OK - Diagnostic trouble codes are present for the other electronic control modules. The Transmission ECU has failed.
Repair: Check the circuit again. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a "Wiggle Test" on the Transmission wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the Transmission wiring harness. It is unlikely that the ECU has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic trouble code is not found, replace the ECU. Prior to replacing an ECU, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Unit - Replace".
STOP