Conditions Which Generate This Code:
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| Illustration 1 | g01551913 |
Schematic of the "Low Idle" Switch | |
This diagnostic code is associated with the "Low Idle" Switch. This switch has two inputs to the ECM: normally open (wire K974-PU) and normally closed (wire K973-PK). During normal operation, one switch input is open and the other input is grounded. If each input is in the same state, the ECM will detect a diagnostic code. This diagnostic code is detected when both switch inputs are open at the same time.
The possible causes of this diagnostic code are listed:
- Short to the ground circuit.
- The circuit is shorted.
- A failed switch
- The ECM may have failed. This is unlikely.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 2977 FMI 04 is active before performing this procedure.
Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.
Test Step 1. CHECK THE CIRCUIT FOR THE SWITCH.
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the J2 engine harness connector from the Engine ECM.
- At the J2 engine harness connector, measure the resistance from contact J2-39 (wire K973-PK) to contact J2-35 (wire K975-WH) with the switch in the Enabled position and the Disable positions.
- At the J2 engine harness connector, measure the resistance from contact J2-52 (wire K974-PU) to contact J2-35 (wire K975-WH) with the switch in the Disabled position and the Enabled position.
Expected Result:
The resistance should measure between approximately 5 ohms, in one position, and greater than 5000 ohms, in the opposite position, for each position of the switch.
Results:
- YES - The resistance is correct for each measurement. Proceed to test step 3.
- NO - The resistance measurement is greater than 5000 ohms for both measurements. The harness or the switch has failed. Proceed to test step 2.
Test Step 2. CHECK FOR A SHORT.
- Disconnect the switch from the harness.
- At the J2 engine harness connector, measure the resistance from contact J2-39 and all other J1 and J2 contacts of the Engine ECM.
- At the J2 engine harness connector, measure the resistance from contact J2-52 and all other J1 and J2 contacts of the Engine ECM.
Expected Result:
The resistance measurement should be greater than 5000 ohms for each measurement.
Results:
- OK - The resistance measurement is greater than 5000 ohms for each measurement.
Repair: Replace the joystick (the low idle switch is not independently serviceable).
Proceed to Test Step 3.
- NOT OK - The resistance measurement is not greater than 5000 ohms for one or more measurements.
Repair: The short is in the circuit with the low resistance measurement. Repair the harness or replace the harness. Verify that the problem has been corrected.
STOP
Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS
- Inspect the contacts of the harness connectors and clean the harness connectors.
- Reconnect all the harness connectors.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Check the status of the CID 2977 FMI 04 diagnostic code.
Expected Result:
The CID 2977 FMI 04 diagnostic code is active.
Results:
- YES - The CID 2977 FMI 04 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 2977 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
STOP