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

The harness code for the Caterpillar Monitoring System must match the application in order to function properly. If the harness code does not match the application, the following problems may occur:

• loss of event notification

• incorrect data displays

• incorrect gauge needle positions

• activation of diagnostic codes

Generally, once an engine is put into service there is no reason to change the harness code. During installation, the customer may decide to install optional sensors or optional gauges that were not initially ordered with the engine. Changing these components may require a different harness code.

Check the current selection for the harness code and compare the current harness code with the description in Systems Operation, "Quad Gauge Module". Determine if the harness code is correct for the application.

There are six pins on the back of the Caterpillar Monitoring System that are used to select the harness code. The pins are grounded or the pins are left open in various combinations for each application. The pins that are grounded are connected to the negative battery terminal block ("TB-2"). The negative battery terminal block ("TB-2") is located on the inside of the Instrument Panel. On the wiring schematic, the negative battery terminal block is labelled as "TB-2".

Because of the large number of wires that are located on the inside of the Electronic Instrument Panel, determining the pins that are connected to the ground becomes difficult to do visually. There are two accurate methods for determining the harness code.

• Harness Code Mode 5 Display (not available on all versions of the Caterpillar Monitoring System)

• A multimeter may be used to check the harness code that is located on the Caterpillar Monitoring Systems without Mode 5.

Note: If a ground wire is connected to "pin A", the harness code pin is not necessarily grounded. The other end of the wire may be tied to the harness and the wire may not be connected to "TB-2". This procedure is done so that the same wiring harness can be used during manufacturing regardless of the harness code.

Procedure For Checking The Harness Code Selection

1. Check The Harness Code Selection Of The Caterpillar Monitoring System.

2. For 153-1929 Engine Monitoring Control (Caterpillar Monitoring System) and earlier modules, proceed to 5.

3. For 155-8653 Engine Monitoring Control (Caterpillar Monitoring System) and newer modules, turn the Engine Control Switch (ECS) to the COOLDOWN/STOP position.

4. In order to check the harness code, use Harness Code Mode 5. For more information about Harness Code Mode 5, see Systems Operation, "Harness Code Mode". STOP.

5. For the 153-1929 Engine Monitoring Control and earlier Caterpillar Monitoring Systems, use a multimeter to check for continuity between the pins for the harness code and Terminal Block 2 (TB-2). Do NOT rely on a visual inspection.

6. The pins that determine the harness code are located on the back of the Caterpillar Monitoring System. The harness code is identified by certain pins of the 40 pin connector. pin 31, pin 3, pin 21, pin 22, pin 16 and pin 6.

7. If a 7x-1708 Multimeter Probe (Red) or a 7x-1709 Multimeter Probe (Black) is available, the continuity check can be made without removing the wires from the 40 pin connector.

8. If the probe adapters are not available, use a 121-9587 Wire Removal Tool to remove the harness code wire from the connector.

9. Record each measurement as the measurements are taken. An example is given below.
   Show/hide table

   Table 1

   	Pin 31	Pin 3	Pin 12	Pin 22	Pin 16	Pin 6
   Measurement	Ground	Open	Open	Ground	Ground	Ground

10. After the harness code has been verified, compare the verified harness code with the Table that is given in Systems Operation, "Quad Gauge Module".

11. The harness code should match the application. If the harness code does not match the application, the following procedure can be used to change the harness code.

Procedure For Changing The Harness Code

Illustration 1	g00608679
Panel Interior Of 3500B Electronic Instrument Panel and Subpanel (1) Caterpillar Monitoring System Module (2) Quad Gauge Clusters (3) Terminal Block 2 (TB-2) (4) Location to tie back the Harness Code Ground Wires If the Wires are not connected to TB-2.

1. Determine The Correct Harness Code For The Application.

   1. In order to determine the correct harness code, refer to Testing And Adjusting, "Quad Guage Module".

   2. Compare the current harness code to the desired harness code.

      Note: One or more of the pins for the Harness Code may need to be grounded in order to change the harness code. Also, one or more of the pins may require grounding to change the harness code. An example is given below.

      Show/hide table

      Table 2

      Application	Mode 5 Harness Code Display	Connections On 40 Pin Connector
      		Pin 31	Pin 3	Pin 12	Pin 22	Pin 16	Pin 6
      Generator Engine With Prime Panel	5	Open	Ground	Open	Ground	Ground	Ground
      Generator Engine With Premium Panel And JWAC	7	Open	Open	Open	Ground	Ground	Ground

   3. Assume that the current harness code is harness code 5 "Generator Engine With Prime Panel" and that the desired harness code is harness code 7 "Generator Engine With Premium Panel And JWAC". Pin 3 should be ungrounded in order to change from harness code 5 to harness code 7.

2. Turn the Engine Control Switch (ECS) to the OFF/RESET position.

   1. In order to change the Harness Code, wires must be grounded or ungrounded.

      Note: Pins are grounded by connecting the pins to the "-Battery" terminal block that is located on the inside of the instrument panel. On the wiring schematic, the terminal block is labelled "TB-2". Refer to 1. A pin for the harness code is not always grounded if a ground wire is connected to the pin. The other end of the wire may be tied in the harness and the wire may not be connected to TB-2. The wire is tied so that the same wiring harness can be used during manufacturing regardless of the harness code.

   2. Grounding A Harness Code Pin. For this step, refer to item 4 in 1. If the wires are not connected to TB-2,the wires can be tied back to this location. The wire can be identified by the printed label at the end of the wire. The label follows the format "EMS (number) TB-2". "Number" represents the pin number of the harness code. The wire terminates at the pin. After locating the wire that needs to be grounded, remove the heat shrink insulation that covers the end of the wire. Ground the wire by connecting the wire to TB-2. Replace the tie wraps as replacement is necessary.

   3. Procedure To Unground A Harness Code Pin. Identify the wire that is described above as being connected to the pin of the Caterpillar Monitoring System that should be ungrounded. Disconnect the end of the wire that is connected to TB-2. Insulate the newly exposed end of the wire and tie back to the harness.

      Note: The new harness code will not take effect until power to the Caterpillar Monitoring System is cycled.

3. Verify That The Harness Code Was Changed Successfully.

   1. Check the harness code by using the Procedure For Checking The Harness Code.