MID 122 - CID 1251 - FMI 03
CAT Comm Adapter 3 478-0235 Diagnostics for Caterpillar
This code is generated in the following situation: The Product Link module tracks machine operating hours and reports them to the office. The alternator R-terminal signal is used to detect when the machine is operating. If the input continuously receives voltage signals above the normal range, machine operation cannot be detected. If the input continuously receives voltage signals above the normal value, the reported timekeeping hours (SMU) will be inaccurate.
Test Procedure 1. Check for a short circuit between the R-terminal cable and the battery.
A. Disconnect the Product Link cable (P1) from the Product Link module.
B. Measure the resistance from alternator R-terminal input J1-4 (403MC9-GN-18) to battery (J1-1). Expected result: The resistance should be greater than 5000 ohms.
Result: • OK - The Product Link harness appears to be normal. Proceed to test step 2.
• Abnormal - The Product Link cable may be short-circuited to the battery.
Repair: Repair the cable and confirm the fault has been eliminated.
Stop Test Step 2. Check for short circuits between the PRODUCT LINK harness and the voltage source.
A. Disconnect the Product Link cable (P1) from the Product Link module.
B. Start the engine.
C. Confirm the presence of a 0 kHz to 2 kHz 11 VDC to 32 VDC square wave by measuring the alternator R-terminal input (J1-4). Additionally, a stable DC voltage equivalent to the battery voltage should be present.
Expected result: No stable voltage equivalent to the battery voltage was measured when measuring the alternator R-terminal input. DC voltage.
Result: • OK - The signal is a 0 kHz to 2 kHz 11 VDC to 32 VDC square wave or a stable DC voltage equivalent to the battery. The Product Link harness may not be faulty. Proceed to Test Step 3.
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• Abnormal - The Product Link cable may be short-circuited to a DC voltage other than the battery voltage. Repair: Repair the cable and confirm the fault has been eliminated.
Stop Test Step 3. Check the machine alternator. A. Disconnect the Product Link machine cable from the alternator.
B. Start the engine.
C. Measure the alternator R terminal to confirm the presence of a 0 kHz to 2 kHz 11 VDC to 32 VDC square wave. There should be no stable DC voltage equivalent to the battery voltage.
Expected Result: There should be a 0 kHz to 2 kHz 11 VDC to 32 VDC square wave at the alternator R terminal.
Result: • OK - There is a square wave at the alternator R terminal. 0 kHz to 2 kHz 11 VDC to 32 VDC square wave. Proceed to Test Step 4.
• Abnormal - No 0 kHz to 2 kHz 11 VDC to 32 VDC square wave at the alternator R-terminal. Repair: Repair or replace the alternator.
Stop Test Step 4. Check if the diagnostic code is still active. A. Clean all contacts on the wiring harness connectors.
B. Reconnect all wiring harness connectors.
C. Turn the key start switch to the ON position and operate the machine.
D. Use a Caterpillar Electronics Technician (Cat ET) to determine if the "CID 1251 FMI 03" diagnostic code is present. Expected Result: The "CID 1251 FMI 03" diagnostic code is present.
Result: • Yes - This fault has not been resolved. The ECM is unlikely to be faulty.
Repair: Re-perform this diagnostic test step. If the cause of this diagnostic code cannot be found, the Product Link ECM should be replaced. Before replacing the Product Link, please contact your Caterpillar technical correspondent. Please refer to System Operation, Troubleshooting & Repair, Testing & Adjustment, "Electronic Control Module (ECM) - Replacement".
Stop • No - No diagnostic code found. The fault does not exist at this time. The initial problem may have been caused by a poor electrical connection or short circuit when disconnecting and reconnecting a wiring harness connector. Restore the machine to normal operation. Stop
CAT Comm Adapter 3 478-0235 Diagnostics for Caterpillar
