AP-1000D, AP-1055D, AP-655C, BG-2255C, BG-2455D and BG-260D Asphalt Pavers MID 030 - CID 0600 - FMI 04 Caterpillar

Conditions Which Generate This Code:

Illustration 1	g00928880

This diagnostic code is recorded when the main display module reads a signal from the sender that is below normal. As a result of this diagnostic code the corresponding gauge will indicate an abnormally high value. The possible causes are listed below:

• The sender has failed.

• The signal circuit in the machine harness is shorted to ground.

• The main display module has failed.

Note: Very low resistance in the sender causes the main display module to read the signal wire as having voltage too low. Low resistance can be caused by a short to ground in the signal circuit. This would cause the corresponding gauge on the display to indicate an abnormally high value. Very high resistance in the sender causes the main display module to read the signal wire as having voltage too high. High resistance can be caused by an open in the signal circuit. The internal circuitry of the main display module would pull a high voltage in the signal wire. This condition is recognized as a gauge that always has an indicator at the far left side of the scale.

Service Notes: Ensure that the desired diagnostic code is on hold. Ensure that the diagnostic code indicator shows "SERV CODE". The schematic that is shown above represents a typical installation of the component. Verify the connector contact and wire numbers by using the Electrical System Schematic for the machine that is being serviced.

Test Step 1. CHECK THE SENDER

1. Turn the disconnect switch and the key start switch to the ON position.

2. Ensure that the diagnostic code is active.

3. Disconnect the sender from the machine harness.

4. Install a jumper wire between the signal wire and ground .

Expected Result:

The diagnostic code changes from being active to being NOT active as the jumper is installed.

Results:

• OK - The diagnostic code will change states as the jumper wire is installed and the jumper wire is removed. The sender has failed. Repeat this test "Check the sender" in order to verify that the sender has failed.

  Repair: Replace the temperature sender (transmission oil).

  Stop.

• NOT OK - The diagnostic code remains active. The diagnostic code does NOT change. The machine harness has failed or the main display module has failed. Proceed to test step 2.

Test Step 2. CHECK FOR A SHORT TO GROUND

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

2. Remove all jumper wires that were previously installed.

3. Disconnect the machine harness connector from the main display module.

4. At the machine harness connector for the main display module, measure the resistance from the signal contact 8 to ground.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

• OK - The resistance measurement is greater than 5000 ohms. The harness is correct. The temperature sender has failed. Replace the sender and verify that the new sender corrects the problem. If the diagnostic code remains exit this procedure. The main display module has failed.

  Repair: It is unlikely that the main display module has failed. Perform this diagnostic code procedure again. If the cause of the diagnostic code is not found, replace the main display module. See Troubleshooting, "Main Display Module - Replace".

  Stop.

• NOT OK - The resistance measurement is NOT greater than 5000 ohms. The machine harness has failed. There is a short in the machine harness. The short is between the signal wire and ground.

  Repair: Repair the machine harness or replace the machine harness.

  Stop.