Asphalt Pavers Conveyor Electronic Control System Caterpillar

Illustration 1	g01117474

Sensor Supply Voltage

This diagnostic code is recorded when the ECM reads the voltage of the sensor supply circuit as below normal range. The sensor supply is a power supply that is internal to the ECM. The sensor supply provides +8 DCV to operate the PWM buffers. The ECM monitors this output voltage and records a diagnostic code when the voltage is is less than 7.5 DCV.

The possible causes of this diagnostic code are:

• The +V circuit is shorted to the return circuit or frame ground.

• A PWM buffer is malfunctioning.

• The ECM has failed. This is unlikely.

System Response:

The results of this diagnostic code are:

• Improper operation of PWM buffers which could cause the conveyors and augers to perform in an unpredictable manner.

Note: Ensure that the diagnostic code CID 061 FMI F04 for the sensor is on hold and that the diagnostic code present indicator on the ECM display is ON. This procedure can cause other diagnostic codes to be recorded. Ignore these created diagnostic codes. When this procedure is completed, clear the created diagnostic codes.

Test Step 1. Check PWM Buffer

1. Turn the key start switch to the ON position. Do not start the engine.

2. While observing the status of the diagnostic code present indicator, individually disconnect the machine harness from each of the following buffers one at a time:

• PWM buffer for the left conveyor ratio dial.

• PWM buffer for the right conveyor ratio dial.

• PWM buffer for the left material height dial.

• PWM buffer for the right material height dial.

Expected Result:

The diagnostic code present indicator turns OFF when one of the PWM buffers is removed from the machine harness.

Results:

• YES - The diagnostic code present indicator does turn OFF when one of the PWM buffers is removed from the machine harness.

  Repair: The circuit is correct. The machine harness and the ECM are operating properly. One of the PWM buffers is malfunctioning. Replace the appropriate PWM buffer.

  Stop.

• NOT OK - The diagnostic code present indicator does not turn OFF when the PWM sensors have been disconnected from the machine harness.

  Repair: The machine harness or the ECM may be malfunctioning.

  Proceed to Test Step 2.

Test Step 2. Check +V Circuit For Short to Return

The machine harness remains disconnected from all of the PWM buffers.

1. Turn the key start switch to the OFF position.

2. Disconnect the machine harness connector from the ECM.

3. At the machine harness connector for the ECM, measure the resistance from circuit at connector contact 40 (P128-BU) to connector contact 39 (P201-GN).

Expected Result:

The resistance should measure greater than 5000 ohms.

Results:

• OK - The resistance measurement is greater than 5000 ohms. Proceed to Test Step 3.

• NOT OK - The resistance measurement is less than 5000 ohms.

  Repair: There is a short in the machine harness for the sensor supply circuit. The short is between the +V circuit (wire P128-BU) or the return circuit (wire P201-GN) of the machine harness. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 3. Check +V Circuit For Short to Ground

The key start switch remains OFF. The PWM buffers and the ECM remain disconnected from the machine harness.

1. At the machine harness connector, measure the resistance from connector contact number 40 (wire P128-BU) to frame ground.

Expected Result:

The resistance should measure greater than 5000 ohms.

Results:

• OK - The resistance measures greater than 5000 ohms. Proceed to Test Step 4.

• NOT OK - The resistance measures less than 5000 ohms.

  Repair: There is a short in the machine harness. The short is between the +V circuit (wire P128-BU) and frame ground. Repair or replace the machine harness.

  Stop.

Test Step 4. Check To See If Diagnostic Code Remains

1. Clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

3. Turn the key start switch to the ON position.

4. Enter service mode 1 on the ECM three digit display. Clear all inactive diagnostic codes.

5. Operate the machine.

6. Check to see if the CID 061 FMI F04 diagnostic code for the sensor supply is present (diagnostic code present indicator ON).

Expected Result:

The CID 061 FMI F04 diagnostic code for the sensor supply is not present.

Results:

• OK - The CID 061 FMI F04 diagnostic code for the sensor supply is not present. The machine harness and the ECM are operating properly.

  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.

• NOT OK - The CID 061 FMI F04 diagnostic code for the sensor supply is still present.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Refer to the Electrical System Schematic for this machine and check all involved wiring harness connectors and wiring. Ensure that the connector contacts are clean and in good condition. Ensure that all machine harness wiring is intact and in good condition. If the cause of this diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace" in this manual.

  Stop.