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| Illustration 1 | g01764475 |
Evaporator Temperature sensor connections | |
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| Illustration 2 | g01896014 |
Location of the Evaporator Temperature sensor | |
A CID 2357 is associated with the Evaporator Temperature sensor. An FMI 04 means the machine ECM has determined the voltage in the sensor circuit is below normal.
Possible causes for this diagnostic code are:
- Failed sensor.
- Sensor circuit shorted to ground.
- Implement ECM failure.ECM failure is unlikely.
Note: Poor connections often cause problems in electrical circuits. Before performing this procedure, inspect all of the harness connectors involved in the circuit. Verify that all circuit connections are clean, secure, and in good condition. If a problem is found with any of the connections: correct the problem, and verify that diagnostic code CID 2357 FMI 04 is still active, before performing the following procedures.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes now, but clear those codes after the original diagnostic code has been corrected.
System Response:
A warning level 1 will be generated.
Test Step 1. CHECK THE SENSOR, ECM, AND HARNESS.
- Turn the disconnect switch, and the key start switch, to the OFF position.
- Disconnect the harness connector from the Evaporator Temperature sensor.
- Turn the disconnect switch, and the key start switch, to the ON position.
- Observe the status of the CID 2357 FMI 04 diagnostic code.
Expected Result:
The diagnostic code remains active and does not change.
Results:
- YES - The diagnostic code remains active and does not change. The sensor is not the problem. Go to Test Step 2.
- NO - The diagnostic code becomes inactive and changes into an active FMI 04 to an FMI 03diagnostic code. The sensor has failed.
Repair: Replace the sensor.
Go to Test Step 3.
Test Step 2. CHECK THE SENSOR CIRCUIT FOR A SHORT TO GROUND.
- Turn the key start switch, and the disconnect switch, to the OFF position.
- The sensor remains disconnected from the harness connector.
- Disconnect the "J1" and "J2" harness connector from the machine ECM.
- At the "J1" ECM harness connector, measure the resistance from contact "J1-30" (wire C554-PK) to all possible sources of ground in the "J1" and "J2" ECM harness connectors.
Expected Result:
Each resistance is greater than 5000 ohms.
Results:
- YES - Each resistance is greater than 5000 ohms. There are no ground shorts in the harness. Go to Test Step 3.
- NO - A resistance measurement is less than 5000 ohms. There is a short in the harness.
Repair: The short is from contact "J1-30" (wire C554-PK) to the circuit with the low resistance measurement. Repair or replace the harness.
Go to Test Step 3.
Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Reconnect all disconnected machine harness connectors. Make sure that all the connectors are clean, and fully seated. Observe that the clips for each connector are securely fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Clear all inactive diagnostic codes.
- Operate the machine.
- Check the status of the CID 2357 FMI 04 diagnostic code.
Expected Result:
The diagnostic code is not active.
Results:
- YES - The diagnostic code is no longer active and does not exist at this time. The problem has been corrected.
Repair: Return machine to normal operation.
STOP
- NO - The diagnostic code is still active. The problem has not been corrected. The ECM may have failed.
Repair: If you have not inspected the harness connectors in a previous Test Step, do that now. Clean the contacts of the harness connectors. Check the wires for damage to the insulation caused by excessive heat, battery acid, or chafing.Perform a 45 N (10 lb.) pull test on each of the wires that are associated with the sensor circuit.Perform a "wiggle test" on the sensor circuit of the machine wiring harness, using the Caterpillar Electronic Technician service tool. The "wiggle test" can be used to detect open or shorted connections in the machine wiring harness.Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened. Perform Test Step 3 again. If the problem was again not found, and the original code is still active, the machine ECM may have failed.Prior to replacing an ECM, always contact your Dealership Technical Communicator for possible consultation with Caterpillar, or with the Dealer Solutions Network. This consultation may greatly reduce repair time. If the ECM needs to be replaced, see Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP