AD30 and AD55 Underground Articulated Trucks Power Train Electronic Control System Caterpillar

Illustration 1	g01043843
Schematic of the retarder indicator (AD55 machine)

Illustration 2	g01043844
Schematic of the retarder indicator (AD30 machine)

Note: Verify that the retarder lever switch is off.

Test Step 1. CHECK THE INDICATOR LAMP

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

2. Replace the indicator lamp with a similar indicator that is known to be correct.

3. Turn the battery disconnect switch and the key start switch to the ON position.

4. Observe the indicator.

Expected Result:

The indicator functions properly.

Results:

• OK - The indicator functions properly during the three second test cycle. Replacing the indicator has corrected the fault.

  STOP

• NOT OK - The indicator does not function correctly. Proceed to Test Step 2.

Test Step 2. CHECK THE HARNESS FOR A SHORT TO FRAME GROUND

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

2. Disconnect the machine harness connectors J1 and J2 from the Power Train/Chassis Electronic Control Module (ECM).

3. Disconnect the indicator from the machine harness.

4. At the machine harness connector J2 for the ECM, measure the resistance from (wire 454-GN(Green)) to all possible sources of frame ground.

Expected Result:

The resistance for each measurement should be greater than 5 ohms.

Results:

• OK - The machine harness is greater than 5 ohms. Proceed to Test Step 3.

• NOT OK - The machine harness is less than 5 ohms.

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

  STOP

Test Step 3. CHECK THE HARNESS FOR A SHORT TO FRAME GROUND

1. At the machine harness from the indicator, measure the resistance from (wire 113-OR(Orange)) to all possible sources of frame ground.

Expected Result:

The resistance that is measured is greater than 5 ohms.

Results:

• OK - The resistance is greater than 5 ohms. Proceed to Test Step 4.

• NOT OK - The resistance is less than 5 ohms. The machine harness has failed.

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

  STOP

Test Step 4. CHECK +BATTERY SUPPLY

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

2. Check for +battery supply at (wire 113-OR(Orange)) of the indicator.

Expected Result:

The voltage should be +battery supply at (wire 113-OR(Orange)).

Results:

• OK - The voltage is +battery supply at (wire 113-OR(Orange)). Proceed to Test Step 5.

• NOT OK - The voltage is below +battery supply.

  Repair: Repair machine harness or replace machine harness.

  STOP

Test Step 5. CHECK HARNESS FOR AN OPEN

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

2. Measure the resistance from contact J2-40 (wire 454-GN(Green)) of the ECM to (wire 454-GN(Green)) of the indicator.

Expected Result:

The resistance that is measured is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 6.

• NOT OK - The resistance is greater than 5 ohms. The machine harness may have failed.

  Repair: Repair machine harness or replace machine harness.

  STOP

Test Step 6. CHECK IF THE PROBLEM REMAINS

1. Inspect the contacts of the harness connectors and clean the harness connectors.

2. Reconnect all the harness connectors.

3. Turn the battery disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Check to see if the fault still occurs.

Expected Result:

The fault is present.

Results:

• YES - The fault is present. The fault 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 fault is not found, replace the ECM. Refer to Systems operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (ECM) - Replace" for the machine that is being serviced.

  STOP

• NO - The fault is no longer present. The fault does not exist at this time.

  Repair: The initial fault 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