RING-RETAINING 3534935 - Caterpillar

Illustration 1 g01116579
PWM Buffer For The Left Conveyor Ratio DialNote: If the CID 021 FMI F01 diagnostic code is only present under certain extreme operating conditions such as dial full clockwise or dial full counterclockwise, the PWM buffer is probably out of specification. Replace the PWM buffer.This diagnostic code is recorded when the ECM reads the PWM buffer signal from the left conveyor ratio dial as below normal or shorted to ground. This procedure checks the PWM buffer. This procedure does not check the conveyor ratio dial.The possible causes of this diagnostic code are:
+V circuit from the ECM to the PWM buffer is open.
Signal circuit shorted to ground.
The PWM buffer is malfunctioning.
The ECM has failed. This is unlikely.System Response:The results of this diagnostic code are:
Conveyor diagnostic lamp on the machine operator's station will be ON.
The auger or conveyor for the left side will either be ON all of the time or OFF all of the time.Note: Ensure that the diagnostic code CID 021 FMI F01 for the PWM buffer is on hold and that the diagnostic code present indicator on the ECM display is ON. This procedure can cause new diagnostic codes to be recorded. Ignore these created codes. When the procedure is completed, clear the created codes.Test Step 1. Check PWM buffer
Turn the key start switch to the ON position.
Access service mode 1. Place the diagnostic code CID 021 FMI F01 on hold. Ensure that the red diagnostic code present indicator on the ECM Display is ON. For more information on service mode 1, refer to the "Accessing Diagnostic Information" module in this manual.
While observing the status of the diagnostic code present indicator, disconnect the machine harness from the PWM buffer.Expected Result:The diagnostic code present indicator on the ECM display turns OFF.Results:
OK - The diagnostic code present indicator on the ECM display turns OFF.Repair: The PWM buffer is malfunctioning. Replace the PWM buffer. Stop.
NOT OK - The diagnostic code present indicator on the ECM display remains ON. The machine harness or the ECM may be malfunctioning. Proceed to Test Step 2.Test Step 2. Check Signal Circuit For Short To GroundThe machine harness remains disconnected from the PWM buffer.
Turn the key start switch to the OFF position.
Disconnect the machine harness from the ECM.
At the machine harness connector for the ECM, measure the resistance from the signal circuit contact "C" (wire P922-PU) to ground.Expected Result:The resistance measurement should be greater than 5000 ohms.Results:
OK - The resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - The resistance measurement is less than 5000 ohms. There is a short in the machine harness. The short is between the signal circuit wire (P922-PU) and a ground source. The possible ground sources are wire P200-BK, wire P201-GN, and frame ground. Repair or replace the machine harness. Stop.Test Step 3. Check To See If Diagnostic Code Remains
Clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the key start switch to the ON position.
Enter service mode