About this article:Caterpillar excavator air conditioning fault code: MID 122 - CID 0168 - FMI 00 troubleshooting
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All R134a products for air conditioning and heating for all Caterpillar machines
NOTE: The Schrader valves used on the high and low pressure sides of the A/C system are located in the 149-2491 A/C Connector Assembly which contains the 3E-4051 Seal Cap and 3E-4057 Valve Assembly on the low pressure side. The 236-9888 A/C Connector Assembly which contains the 3E-4052 Seal Cap and 3E-4058 Valve Assembly on the high pressure side. NOTE: The portable flushing unit is only permitted when using 153-8538 Refrigerant Flushing Fluid and all procedures should be performed in accordance with Testing and Adjusting, SENR5664, "Refrigerator Systems - Flushing". Refrigerant flushing fluid may only be reused after filtering.
Conditions that generate this code:
This diagnostic code is logged when the diagnostic circuitry within Product Link detects a system voltage greater than 32 VDC.
Possible causes of this fault are as follows:
• A charging system component has failed.
• A harness wire has failed.
• There is a fault in the Product Link, but Product Link is not likely to be
NOTE: Determine if a battery charger or welder is in use on the machine. Disconnect any charger or welder in use.
Recheck for diagnostic codes.
TEST PROCEDURE 1. CHECK PRODUCT LINK SYSTEM VOLTAGE.
A. Start the engine and run it at high idle for 5 to 10 minutes.
B. Measure the system voltage between the "Unswitched Power" and "Ground" contacts. Pin 52 is the "Unswitched Power" terminal and pin 65 is the "Ground" terminal.
Expected Results:
The voltage is 11 VDC to 32 VDC.
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Result:
• OK - The voltage is 11 VDC to 32 VDC. Product Link should not log this diagnostic code.
Repair: Clear the diagnostic code from Product Link using Caterpillar Electronic Technician (Cat ET). If the voltage is OK and Product Link logs this diagnostic code again, the Product Link may need to be replaced. Before replacing the Product Link, contact your Caterpillar Technical Communicator.
STOP
• NOT OK - Voltage is not 11 VDC to 32 VDC. Go to Test Step 2.
TEST STEP 2. CHECK THE ALTERNATOR.
A. Run the engine at high idle for 5 to 10 minutes.
B. Measure the voltage output at the battery terminals.
EXPECTED RESULT:
The voltage should be less than 32 VDC.
RESULTS:
• OK - Voltage is less than 32 VDC. The battery may be faulty. Go to Test Step 3.
• NOT OK - Voltage is greater than 32 VDC. Troubleshoot the alternator. The voltage regulator may be faulty. If the condition is not corrected, go to Test Step 3.
TEST STEP 3. CHECK THE BATTERY VOLTAGE.
Turn the key start switch to the OFF position. Measure the voltage at the battery terminals.
EXPECTED RESULT:
The voltage should be less than 32 VDC.
Result:
• OK - Voltage is less than 32 DCV. Go to Test Step 4.
• NO - Voltage is greater than 32 VDC.
Repair: Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
If the condition is not corrected, go to Test Step 4.
Test Step 4. Check each ECM on the machine.
Check the recorded diagnostic codes for other ECMs installed on the machine. Compare each ECM that has a recorded "CID 168 FMI 00" code for the same time period.
Note: The recorded service meter hours (SMH) may be different. The difference between the current SMH and the recorded SMH is significant.
Expected Results:
Other "CID 168 FMI 00" diagnostic codes may be found on other Electronic Control Modules (ECMs).
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Result:
• Yes - Additional "CID 168 FMI 00" diagnostic codes can be found on other Electronic Control Modules (ECMs).
Fix: Clear fault if all of the following occur:
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◦ No faults were found in the charging system.
◦ No faults were found in the wiring.
◦ The fault has recurred several times.
Monitor the module and machine for further faults. If the fault recurs, the Product Link module is not the problem since other Electronic Control Modules are showing the same fault. Recheck system voltages.
Stop
• No - Additional "CID 168 FMI 00" diagnostic codes cannot be found on other Electronic Control Modules (ECMs).
Fix: Clear fault if all of the following occur:
◦ No faults were found in the charging system.
◦ No fault is found in the wiring.
◦ The fault has recurred several times.
Monitor the module and machine for further faults. If the fault recurs, the Product Link module may be faulty. The Product Link should be replaced. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (ECM) - Replace". After replacing the Product Link, recheck the system and check the status of the diagnostic codes.
Stop
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