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

The Scroll Switch Does Not Scroll

This procedure is for the "SCROLL" switch that does not scroll parameter values in the Display Area. The "Does Not Scroll" condition 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 "SCROLL" 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 the corroded terminals and tighten the loose connections.

2. Check The Harness.

   1. Disconnect the signal wire from the switch.

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

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

      Expected Result: The Display Area should scroll from one parameter value to the next parameter value.

      Results:

      • OK - The Display Area scrolls from one parameter value to the next parameter value. The circuit is operating correctly. The switch has a problem. Check the switch or replace the switch.

      • Not OK - The Display Area does not scroll from one parameter value to the next parameter value. The signal wire for 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 signal wire to the ground wire. If a ground wire is not near, connect the signal wire to battery ground.

   3. On the Electrical System Schematic, trace the signal wire from the switch to the Main Display Module. The contact that is used for the signal connector at the Main Display Module is contact 23.

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

   5. At the engine harness connector for the Main Display Module, measure the resistance between the signal contact and contact 2 (ground).

      Expected Result: 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. Replace the Main Display Module. For more information on this subject, see Testing And Adjusting, "Module - Replace".

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

The Scroll Switch Continually Scrolls

This procedure is for the "SCROLL" switch that continually scrolls parameter values in the Display Area. The "Continually Scrolls" condition is probably caused by a short to ground. Also, the Main Display Module may cause this problem (unlikely condition).

1. Locate The Switch.

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

   2. Locate the "SCROLL" 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 signal wire from the "SCROLL" switch.

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

      Expected Result: The Display Area should NOT scroll from one parameter value to the next parameter value.

      Results:

      • OK - The Display Area does NOT scroll from one parameter to the next parameter. The circuit is operating correctly. The switch has a problem. Check or replace the switch.

      • Not OK - The Display Area scrolls from one parameter to the next parameter. 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 signal wire remains disconnected from the switch. Do Not allow the contact to touch any other components.

   2. On the Electrical System Schematic, trace the signal wire from the switch to the Main Display Module. The Signal Contact at the Main Display Module is 23.

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

   4. At the engine harness connector for the Main Display Module, measure the resistance between Signal Contact 23 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 a short between ground and the signal wire in the engine harness. Repair the engine harness or replace the engine harness.