3508, 3508B, 3508C, 3512, 3512B, 3512C, 3516, 3516B and 3516C Engines Caterpillar Monitoring System Caterpillar

The "CLEAR/MODE" Switch Does NOT Clear Logged Diagnostic Codes and Tattletale Values or Does NOT Initiate Mode Changes

This procedure is for the "CLEAR/MODE" switch that will not clear logged diagnostic codes and the "CLEAR/MODE" switch that will not clear "tattletale values". Also, this procedure is for the "CLEAR/MODE" switch that does NOT initiate mode changes on the Display Area. The "Does NOT Clear" Logged Diagnostic Codes and Tattletale Values or "Does Not Initiate Mode Changes" condition is probably caused by an undesired open circuit. Also, the Main Display Module can be the cause of the problem (unlikely condition).

1. Locate The Switch.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Locate the "CLEAR/MODE" switch. If necessary, use the Electrical System Schematic to assist in locating the switch.

   3. Check for loose terminal connections or corroded terminal connections.

   4. Clean corroded terminals and tighten loose connections.

2. Check The Harness.

   1. Disconnect the "CLEAR" signal wire from the "CLEAR/MODE" switch.

   2. Turn the "ECS" switch to the COOLDOWN/STOP position.

   3. Alternately, ground the "CLEAR" signal wire and float the "CLEAR" signal wire.

      Expected Result: The Display Area should clear the diagnostic codes or tattletale values.

      Results:

      • OK - The Display Area clears the diagnostic codes or the tattletale values. The circuit is operating correctly. The switch has a problem. Check the switch or replace the switch.

      • Not OK - The Display Area Does Not clear logged diagnostic codes or tattletale values. The signal wire in the engine harness probably has an open circuit. Proceed to Step 3.

3. Check The Harness.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Connect a jumper wire from the "CLEAR" signal wire to the ground wire. If a ground wire is not near, connect the "CLEAR" signal wire to battery ground.

   3. On the Electrical System Schematic, trace the "CLEAR" signal wire from the switch to the Main Display Module.

   4. The "CLEAR" signal is contact 33 at the Main Display Module.

   5. Disconnect the engine harness from the Main Display Module.

   6. At the engine harness connector for the Main Display Module, measure the resistance between the "CLEAR" Signal Contact and Contact 2 (ground).

      Expected Results: The resistance should be less than 5 ohms.

      Results:

      • OK - The resistance is less than 5 ohms. The harness resistance is correct. The Main Display Module has a problem. There is an open between ground and the "CLEAR" signal wire in the engine harness.

      • Not OK - The resistance is greater than 5 ohms. The engine harness has a problem. There is an open between ground and the "CLEAR" signal wire in the engine harness. Repair the engine harness or replace the engine harness.

The "CLEAR/MODE" Switch Automatically Clears Logged Diagnostic Codes and Tattletale Values or Does Not Initiate Mode Changes

This procedure is for the "CLEAR/MODE" switch that "Automatically Logged" Diagnostic Codes and Tattletale Values on the Display Area. The "Does Not Clear Logged Diagnostic Codes" and Tattletale values or "Does Not Initiate Mode Changes" is probably caused by an undesired open circuit. Also, the Main Display Module may cause the problem (unlikely condition).

1. Locate The Switch.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Locate the "CLEAR/MODE" switch. If necessary, use the Electrical System Schematic to assist in locating the switch.

   3. Check for loose terminal connections or corroded terminal connections to the switch.

   4. Clean corroded terminals and tighten loose connections.

2. Check The Harness.

   1. Disconnect the "CLEAR" signal wire from the "CLEAR/MODE" switch.

   2. Turn the "ECS" switch to the COOLDOWN/STOP position.

      Expected Result: The Display Area should NOT clear diagnostic codes or tattletale values.

      Results:

      • OK - The Display Area does NOT clear diagnostic codes or tattletale values. The circuit is operating correctly. The switch has a problem. Check the switch or replace the switch.

      • Not OK - The Display Area continues to clear logged diagnostic codes or tattletale values. The engine harness is shorted to ground or the Main Display Module has a problem. Proceed to Step 3.

3. Check The Harness.

   1. Turn the "ECS" switch to the OFF/RESET position.

      Note: The "CLEAR" signal wire remains disconnected from the switch. Do Not allow the contact to touch any components.

   2. On the Electrical System Schematic, trace the "CLEAR" signal wire from the switch to the Main Display Module. The "CLEAR" signal contact is number 33 at the Main Display Module.

   3. Disconnect the engine harness from the Main Display Module.

   4. At the engine harness connector for the Main Display Module, measure the resistance that is between the "CLEAR" Signal Contact 33 and Contact 2 (ground).

      Expected Result: The resistance should be greater than 5000 ohms.

      Results:

      • OK - The resistance is greater than 5000 ohms. The harness resistance is correct. The Main Display Module has a problem. Replace the Main Display Module. For more information on this subject, see Testing And Adjusting, "Module - Replace".

      • Not OK - The resistance is less than 5000 ohms. The engine harness has a problem. There is an open between ground and the "CLEAR" signal wire in the engine harness. Repair the engine harness or replace the engine harness.